Ethylene-to-liquids systems and methods

ABSTRACT

Integrated systems are provided for the production of higher hydrocarbon compositions, for example liquid hydrocarbon compositions, from methane using an oxidative coupling of methane system to convert methane to ethylene, followed by conversion of ethylene to selectable higher hydrocarbon products. Integrated systems and processes are provided that process methane through to these higher hydrocarbon products.

CROSS-REFERENCE

This application is a continuation application of U.S. patentapplication Ser. No. 16/197,984, filed Nov. 21, 2018, which is acontinuation application of U.S. patent application Ser. No. 15/335,183,filed Oct. 26, 2016, which is a continuation application of U.S. patentapplication Ser. No. 15/076,512, filed Mar. 21, 2016, now U.S. Pat. No.9,512,047, which is a continuation application of U.S. patentapplication Ser. No. 14/789,917, filed Jul. 1, 2015, now U.S. Pat. No.9,321,702, which is a continuation application of U.S. patentapplication Ser. No. 14/591,850, filed Jan. 7, 2015, which claims thebenefit of U.S. Provisional Patent Application Ser. No. 61/925,200,filed Jan. 8, 2014, U.S. Provisional Patent Application Ser. No.62/010,986, filed Jun. 11, 2014, and U.S. Provisional Patent ApplicationSer. No. 62/050,729, filed Sep. 15, 2014, each of which is entirelyincorporated herein by reference.

BACKGROUND

The modern petrochemical industry makes extensive use of cracking andfractionation technology to produce and separate various desirablecompounds from crude oil. Cracking and fractionation operations areenergy intensive and generate considerable quantities of greenhousegases.

The gradual depletion of worldwide petroleum reserves and thecommensurate increase in petroleum prices may place extraordinarypressure on refiners to minimize losses and improve efficiency whenproducing products from existing feedstocks, and also to seek viablealternative feedstocks capable of providing affordable hydrocarbonintermediates and liquid fuels to downstream consumers.

Methane may provide an attractive alternative feedstock for theproduction of hydrocarbon intermediates and liquid fuels due to itswidespread availability and relatively low cost when compared to crudeoil. Worldwide methane reserves may be in the hundreds of years atcurrent consumption rates and new production stimulation technologiesmay make formerly unattractive methane deposits commercially viable.

Ethylene is an important commodity chemical intermediate. It may be usedin the production of polyethylene plastics, polyvinyl chloride, ethyleneoxide, ethylene chloride, ethylbenzene, alpha-olefins, linear alcohols,vinyl acetate, and fuel blendstocks such as, but not limited to,aromatics, alkanes and alkenes. With economic growth in developed anddeveloping portions of the world, demand for ethylene and ethylene basedderivatives continues to increase. Currently, ethylene is producedthrough the cracking of ethane derived either from crude oildistillates, called naphtha, or from the relatively minor ethanecomponent of natural gas. Ethylene production is primarily limited tohigh volume production as a commodity chemical in relatively large steamcrackers or other petrochemical complexes that also process the largenumber of other hydrocarbon byproducts generated in the crude oilcracking process. Producing ethylene from far more abundant andsignificantly less expensive methane in natural gas provides anattractive alternative to ethylene derived from ethane in natural gas orcrude oil.

SUMMARY

Recognized herein is the need for efficient and commercially viablesystems and methods for converting ethylene to higher molecular weighthydrocarbons, including gasoline, diesel fuel, jet fuel, and aromaticchemicals. In some cases, the higher molecular weight hydrocarbons canbe produced from methane in an integrated process that converts methaneto ethylene and the ethylene to the higher molecular weight compounds.An oxidative coupling of methane (“OCM”) reaction is a process by whichmethane can form one or more hydrocarbon compounds with two or morecarbon atoms (also “C₂₊ compounds” herein), such as olefins likeethylene.

In an OCM process, methane can be oxidized to yield products comprisingC₂₊ compounds, including alkanes (e.g., ethane, propane, butane,pentane, etc.) and alkenes (e.g., ethylene, propylene, etc.). Suchalkane (also “paraffin” herein) products may not be suitable for use indownstream processes. Unsaturated chemical compounds, such as alkenes(or olefins), may be more preferable for use in downstream processes.Such compounds may be polymerized to yield polymeric materials, whichmay be employed for use in various commercial settings.

Oligomerization processes can be used to further convert ethylene intolonger chain hydrocarbons useful as polymer components for plastics,vinyls, and other high value polymeric products. Additionally, theseoligomerization processes may be used to convert ethylene to otherlonger hydrocarbons, such as C₆, C₇, C₈ and longer hydrocarbons usefulfor fuels like gasoline, diesel, jet fuel and blendstocks for thesefuels, as well as other high value specialty chemicals.

An aspect of the present disclosure provides an oxidative coupling ofmethane (OCM) system, comprising: (a) an OCM subsystem that (i) takes asinput a feed stream comprising methane (CH₄) and a feed streamcomprising an oxidizing agent, and (ii) generates from the methane andthe oxidizing agent a product stream comprising C₂₊ compounds andnon-C₂₊ impurities; (b) at least one separations subsystem downstreamof, and fluidically coupled to, the OCM subsystem, wherein theseparations subsystem comprises a first heat exchanger, a de-methanizerunit downstream of the first heat exchanger, and a second heat exchangerdownstream of the de-methanizer unit, wherein (i) the first heatexchanger cools the product stream, (ii) the de-methanizer unit acceptsthe product stream from the first heat exchanger and generates anoverhead stream comprising at least a portion of the non-C₂₊ impurities,and (iii) at least a portion of the overhead stream is cooled in thesecond heat exchanger and is subsequently directed to the first heatexchanger to cool the product stream; and (c) an olefin to liquidssubsystem downstream of the OCM subsystem, wherein the olefin to liquidssubsystem is configured to generate higher hydrocarbon(s) from one ormore olefins included in the C₂₊ compounds.

In some embodiments of aspects provided herein, the oxidizing agent isO₂. In some embodiments of aspects provided herein, the O₂ is providedby air. In some embodiments of aspects provided herein, the OCMsubsystem comprises at least one OCM reactor. In some embodiments ofaspects provided herein, the OCM subsystem comprises at least onepost-bed cracking unit downstream of the at least one OCM reactor, whichpost-bed cracking unit is configured to convert at least a portion ofalkanes in the product stream to alkenes. In some embodiments of aspectsprovided herein, the system further comprises a non-OCM process upstreamof the OCM subsystem. In some embodiments of aspects provided herein,the non-OCM process is a natural gas liquids process. In someembodiments of aspects provided herein, the post-bed cracking unit isconfigured to receive an additional stream comprising propane,separately from the product stream. In some embodiments of aspectsprovided herein, the non-C₂₊ impurities comprise one or more of nitrogen(N₂), oxygen (O₂), water (H₂O), argon (Ar), carbon monoxide (CO), carbondioxide (CO₂), hydrogen (H₂) and methane (CH₄). In some embodiments ofaspects provided herein, the higher hydrocarbon is a higher molecularweight hydrocarbon.

An aspect of the present disclosure provides an oxidative coupling ofmethane (OCM) system, comprising: (a) an OCM subsystem that (i) takes asinput a feed stream comprising methane (CH₄) and a feed streamcomprising an oxidizing agent, and (ii) generates from the methane andthe oxidizing agent a product stream comprising C₂₊ compounds andnon-C₂₊ impurities; (b) at least one methanation subsystem downstreamof, and fluidically coupled to, the OCM subsystem, wherein themethanation subsystem reacts CO, CO₂ and H₂ included in the non-C₂₊impurities to generate methane; and (c) an ethylene-to-liquids (ETL)subsystem downstream of the OCM subsystem, wherein the ETL subsystem isconfigured to generate higher hydrocarbon(s) from ethylene included inthe C₂₊ compounds.

In some embodiments of aspects provided herein, at least a portion ofthe methane generated in the methanation subsystem is recycled to theOCM subsystem. In some embodiments of aspects provided herein, theoxidizing agent is O₂. In some embodiments of aspects provided herein,the O₂ is provided by air. In some embodiments of aspects providedherein, the OCM subsystem comprises at least one OCM reactor. In someembodiments of aspects provided herein, the OCM subsystem comprises atleast one post-bed cracking unit downstream of the at least one OCMreactor, which post-bed cracking unit is configured to convert at leasta portion of alkanes in the product stream to alkenes. In someembodiments of aspects provided herein, the system further comprises anon-OCM process upstream of the OCM subsystem. In some embodiments ofaspects provided herein, the non-OCM process is a natural gas liquidsprocess. In some embodiments of aspects provided herein, the post-bedcracking unit is configured to receive an additional stream comprisingpropane, separately from the product stream. In some embodiments ofaspects provided herein, the higher hydrocarbon(s) comprise aromatics.In some embodiments of aspects provided herein, the non-C₂₊ impuritiescomprise one or more of nitrogen (N₂), oxygen (O₂), water (H₂O), argon(Ar), carbon monoxide (CO), carbon dioxide (CO₂), hydrogen (H₂) andmethane (CH₄). In some embodiments of aspects provided herein, themethanation subsystem comprises at least one methanation reactor.

An aspect of the present disclosure provides a method of producing aplurality of hydrocarbon products, the method comprising: (a)introducing methane and a source of oxidant into an oxidative couplingof methane (OCM) reactor system capable of converting methane toethylene at reactor inlet temperatures of between about 450° C. and 600°C. and reactor pressures of between about 15 psig and 125 psig, with C₂₊selectivity of at least about 50%, under conditions for the conversionof methane to ethylene; (b) converting methane to a product gascomprising ethylene; (c) introducing separate portions of the productgas into at least a first and second integrated ethylene conversionreaction systems, each integrated ethylene conversion reaction systembeing configured for converting ethylene into a different higherhydrocarbon product; and (d) converting the ethylene into differenthigher hydrocarbon products.

In some embodiments of aspects provided herein, the first and secondintegrated ethylene conversion systems are selected from the groupconsisting of selective and full range ethylene conversion systems. Insome embodiments of aspects provided herein, the method furthercomprises introducing a portion of the product gas into a thirdintegrated ethylene conversion system. In some embodiments of aspectsprovided herein, the method further comprises introducing a portion ofthe product gas into a fourth integrated ethylene conversion systems. Insome embodiments of aspects provided herein, the at least first andsecond integrated ethylene conversion systems are selected from thegroup consisting of linear alpha olefin (LAO) systems, linear olefinsystems, branched olefin systems, saturated linear hydrocarbon systems,branched hydrocarbon systems, saturated cyclic hydrocarbon systems,olefinic cyclic hydrocarbon systems, aromatic hydrocarbon systems,oxygenated hydrocarbon systems, halogenated hydrocarbon systems,alkylated aromatic systems, and hydrocarbon polymer systems. In someembodiments of aspects provided herein, the first and second ethyleneconversion systems are selected from the group consisting of LAO systemsthat produce one or more of 1-butene, 1-hexene, 1-octene and 1-decene.In some embodiments of aspects provided herein, at least one of the LAOsystems is configured for performing a selective LAO process. In someembodiments of aspects provided herein, the first or second integratedethylene conversion systems comprises a full range ethyleneoligomerization system configured for producing higher hydrocarbons inthe range of C₃ to C₃₀. In some embodiments of aspects provided herein,the OCM reactor system comprises nanowire OCM catalyst material. In someembodiments of aspects provided herein, the product gas comprises lessthan 5 mol % of ethylene. In some embodiments of aspects providedherein, the product gas comprises less than 3 mol % of ethylene. In someembodiments of aspects provided herein, the product gas furthercomprises one or more gases selected from the group consisting of CO₂,CO, H₂, H₂O, C₂H₆, CH₄ and C₃₊ hydrocarbons. In some embodiments ofaspects provided herein, the method further comprises enriching theproduct gas for ethylene prior to introducing the separate portions ofthe product gas into the at least first and second integrated ethyleneconversion reaction systems. In some embodiments of aspects providedherein, the method further comprises introducing an effluent gas fromthe first or second integrated ethylene conversion reaction systems intothe OCM reactor system.

An aspect of the present disclosure provides a method of producing aplurality of liquid hydrocarbon products, the method comprising: (a)catalytically converting methane to a product gas comprising ethylene;and (b) processing separate portions of the product gas with at leasttwo discrete catalytic reaction systems selected from the groupconsisting of linear alpha olefin (LAO) systems, linear olefin systems,branched olefin systems, saturated linear hydrocarbon systems, branchedhydrocarbon systems, saturated cyclic hydrocarbon systems, olefiniccyclic hydrocarbon systems, aromatic hydrocarbon systems, oxygenatedhydrocarbon systems, halogenated hydrocarbon systems, alkylated aromaticsystems, and hydrocarbon polymer systems.

An aspect of the present disclosure provides a processing system,comprising: (a) an oxidative coupling of methane (OCM) reactor systemcomprising an OCM catalyst, the OCM reactor system being fluidlyconnected at an input to a source of methane and a source of oxidant,wherein the OCM reactor system (i) takes as input the methane and theoxidant and (ii) generates from the methane and the oxidant a productstream comprising C₂₊ compounds; (b) at least a first catalytic ethyleneconversion reactor systems and a second catalytic ethylene conversionreactor system downstream of the OCM reactor system, the first catalyticethylene reactor system being configured to convert ethylene to a firsthigher hydrocarbon, and the second catalytic ethylene reactor systembeing configured to convert ethylene to a second higher hydrocarbondifferent from the first higher hydrocarbon; and (c) a selectivecoupling unit between the OCM reactor system and the first and secondcatalytic ethylene reactor systems, which selective coupling unit isconfigured to selectively direct at least a portion of the product gasto each of the first and second catalytic ethylene reactor systems.

In some embodiments of aspects provided herein, the first and secondethylene conversion systems are selected from the group consisting oflinear alpha olefin (LAO) systems, linear olefin systems, branchedolefin systems, saturated linear hydrocarbon systems, branchedhydrocarbon systems, saturated cyclic hydrocarbon systems, olefiniccyclic hydrocarbon systems, aromatic hydrocarbon systems, oxygenatedhydrocarbon systems, halogenated hydrocarbon systems, alkylated aromaticsystems, ethylene copolymerization systems, and hydrocarbon polymersystems. In some embodiments of aspects provided herein, the OCMcatalyst comprises a nanowire catalyst. In some embodiments of aspectsprovided herein, the system further comprises an ethylene recoverysystem between the OCM reactor system and the first and second catalyticethylene conversion reactor systems, the ethylene recovery systemconfigured to enrich the product gas for ethylene.

An aspect of the present disclosure provides a chemical productionsystem, comprising: an OCM subsystem that includes an OCM reactor,wherein the OCM reactor (i) takes as input a feed stream comprisingmethane (CH₄) and a feed stream comprising an oxidizing agent and (ii)generates from the methane and the oxidizing agent C₂₊ compounds andnon-C₂₊ impurities; and an ethylene-to-liquids (ETL) subsystemdownstream of the OCM subsystem that includes an ETL reactor, whereinthe ETL reactor converts at least a portion of the C₂₊ compounds to aproduct stream comprising C₃₊ compounds, which C₃₊ compounds aregenerated at a single pass conversion of at least about 40%.

In some embodiments of aspects provided herein, the methane is from anon-OCM process. In some embodiments of aspects provided herein, the ETLreactor operates at a pressure between about 4 bar and 50 bar. In someembodiments of aspects provided herein, the single pass conversion is atleast about 40% without recycle.

An aspect of the present disclosure provides a method for generatinghydrocarbons, comprising: (a) directing a feed stream comprising methane(CH₄) and a feed stream comprising an oxidizing agent to an OCM reactor;(b) in the OCM reactor, generating an OCM product stream comprising C₂₊compounds and non-C₂₊ impurities from the methane and the oxidizingagent; (c) directing at least a portion of the C₂₊ compounds to anethylene-to-liquids (ETL) subsystem downstream of the OCM subsystem,wherein the ETL subsystem has an ETL reactor that converts at least aportion of the C₂₊ compounds in the OCM product stream to an ETL productstream comprising C₃₊ compounds; and (d) recycling less than 25% ofethylene in the product stream to the ETL subsystem.

In some embodiments of aspects provided herein, the OCM and ETLsubsystems generate the C₃₊ compounds at a single pass conversionefficiency of at least about 40%. In some embodiments of aspectsprovided herein, the single pass conversion efficiency is at least about40% without recycle. In some embodiments of aspects provided herein, themethane is from a non-OCM process. In some embodiments of aspectsprovided herein, the ETL reactor operates at a pressure between about 10bar and 50 bar.

An aspect of the present disclosure provides a method for generating acatalyst, comprising: (a) providing a catalyst base material having afirst set of pores, wherein the base material comprises an activecomponent that facilitates the conversion of olefins to a first set ofhydrocarbons, at least some of which is in liquid form at roomtemperature and atmospheric pressure; (b) introducing a second set ofpores into the base material having an average diameter of at leastabout 10 nanometers as measured by BET isotherms; and (c) providing oneor more dopants on one or more surfaces of the base material, whereinthe one or more dopants facilitate the conversion of olefins to a secondset of hydrocarbons, at least some of which are in liquid form at roomtemperature and atmospheric pressure, wherein the second set ofhydrocarbons has a different product distribution than the first set ofhydrocarbons.

In some embodiments of aspects provided herein, the first set of poreshave an average diameter from at least about 4 Angstroms to 10Angstroms. In some embodiments of aspects provided herein, the basematerial comprises a zeolite. In some embodiments of aspects providedherein, (b) is subsequent to (c). In some embodiments of aspectsprovided herein, (b) and (c) are performed simultaneously. In someembodiments of aspects provided herein, the base material has a surfacearea from about 100 m²/g to 1000 m²/g. In some embodiments of aspectsprovided herein, (c) comprises providing dopants selected from the groupconsisting of Ga, Zn, Al, In, Ni, Mg, B and Ag. In some embodiments ofaspects provided herein, the catalyst base material is H—Al-ZSM-5,H—Ga—ZSM-5, H—Fe—ZSM-5, H—B—ZSM-5, or any combination thereof. In someembodiments of aspects provided herein, the second set of hydrocarbonshas a narrower product distribution than the first set of hydrocarbons.

An aspect of the present disclosure provides a system for generatinghydrocarbons, comprising: an ethylene-to-liquids (ETL) unit comprisingone or more ETL reactors, wherein an individual ETL reactor acceptsethylene from a non-ETL process and generates a product streamcomprising higher hydrocarbons through an oligomerization process,wherein at least some of the higher hydrocarbons are in liquid form atroom temperature and atmospheric pressure; and at least one separationsunit downstream of, and fluidically coupled to, the ETL unit, whereinthe separations unit separates the product stream into individualstreams, each comprising a subset of the higher hydrocarbons.

In some embodiments of aspects provided herein, the ETL reactorcomprises a catalyst having an active material and one or more dopantson surfaces of the active material. In some embodiments of aspectsprovided herein, the system further comprises an oxidative coupling ofmethane (OCM) unit upstream of the ETL unit, wherein the OCM unitcomprises one or more OCM reactors, each of which (i) takes as input afeed stream comprising methane (CH₄) and a feed stream comprising anoxidizing agent, (ii) generates from the methane and the oxidizing agentC₂₊ compounds and non-C₂₊ impurities, and (iii) directs at least asubset of ethylene in the C₂₊ compounds to the ETL unit.

An aspect of the present disclosure provides a catalyst for theconversion of ethylene to liquid hydrocarbon fuels, the catalystcomprising: (a) a ZSM-5 base material; (b) a binder material; and (c) adopant material; wherein the catalyst has a cycle lifetime of at leastabout 1 week when in contact with up to about 100 parts per million(ppm) acetylene, and wherein the catalyst has a replacement lifetime ofat least about 1 year when in contact with up to about 100 ppmacetylene.

An aspect of the present disclosure provides a catalyst forhydrogenation of acetylene in an oxidative coupling of methane (OCM) andethylene to liquids (ETL) process comprising at least one elementalmetal, wherein the catalyst is capable of decreasing the concentrationof acetylene to less than about 100 parts per million (ppm) in an OCMeffluent prior to flowing the OCM effluent into an ETL process.

In some embodiments of aspects provided herein, the catalyst is capableof decreasing the concentration of acetylene to less than about 10 ppmin the OCM effluent. In some embodiments of aspects provided herein, thecatalyst is capable of decreasing the concentration of acetylene to lessthan about 1 ppm in the OCM effluent. In some embodiments of aspectsprovided herein, the at least one elemental metal includes palladium. Insome embodiments of aspects provided herein, the at least one elementalmetal is part of a metal oxide. In some embodiments of aspects providedherein, the catalyst is capable of providing an OCM effluent thatcomprises at least about 0.5% carbon monoxide. In some embodiments ofaspects provided herein, the catalyst is capable of providing an OCMeffluent that comprises at least about 1% carbon monoxide. In someembodiments of aspects provided herein, the catalyst is capable ofproviding an OCM effluent that comprises at least about 3% carbonmonoxide. In some embodiments of aspects provided herein, the catalysthas a lifetime of at least about 1 year. In some embodiments of aspectsprovided herein, the catalyst is capable of providing an OCM effluentthat comprises at least about 0.1% acetylene. In some embodiments ofaspects provided herein, the catalyst is capable of providing an OCMeffluent that comprises at least about 0.3% acetylene. In someembodiments of aspects provided herein, the catalyst is capable ofproviding an OCM effluent that comprises at least about 0.5% acetylene.In some embodiments of aspects provided herein, the ETL process convertsethylene in the OCM effluent into higher hydrocarbon(s). In someembodiments of aspects provided herein, the at least one metal comprisesa plurality of metals.

An aspect of the present disclosure provides a catalyst for convertingcarbon monoxide (CO) and/or carbon dioxide (CO₂) into methane (CH₄) inan oxidative coupling of methane (OCM) and ethylene to liquids (ETL)process, wherein the catalyst comprises at least one elemental metal,and wherein the catalyst converts CO and/or CO₂ into CH₄ at aselectivity for the formation of methane that is at least about 10-foldgreater than the selectivity of the catalyst for formation of coke in anETL effluent.

In some embodiments of aspects provided herein, the catalyst has aselectivity for the formation of methane that is at least about 100-foldgreater than the selectivity of the catalyst for formation of coke. Insome embodiments of aspects provided herein, the catalyst has aselectivity for the formation of methane that is at least about1000-fold greater than the selectivity of the catalyst for formation ofcoke. In some embodiments of aspects provided herein, the catalyst has aselectivity for the formation of methane that is at least about10000-fold greater than the selectivity of the catalyst for formation ofcoke. In some embodiments of aspects provided herein, the ETL effluentcomprises at least about 3% olefin and/or acetylene compounds. In someembodiments of aspects provided herein, the ETL effluent comprises atleast about 5% olefin and/or acetylene compounds. In some embodiments ofaspects provided herein, the ETL effluent comprises at least about 10%olefin and/or acetylene compounds. In some embodiments of aspectsprovided herein, the at least one elemental metal includes nickel. Insome embodiments of aspects provided herein, the at least one elementalmetal is part of a metal oxide.

An aspect of the present disclosure provides a method for preventingcoke formation on a methanation catalyst in an oxidative coupling ofmethane (OCM) and ethylene to liquids (ETL) process, the methodcomprising: (a) providing an ETL effluent comprising carbon monoxide(CO) and/or carbon dioxide (CO₂); and (b) using a methanation catalystto perform a methanation reaction with the ETL effluent, wherein: (i)hydrogen and/or water is added to the ETL effluent prior to (b); (ii)olefins and/or acetylene in the ETL effluent is hydrogenated prior to(b); and/or (iii) olefins and/or acetylene are separated and/orcondensed from the ETL effluent prior to (b).

In some embodiments of aspects provided herein, (iii) is performed usingabsorption or adsorption. In some embodiments of aspects providedherein, the methanation reaction forms at least about 1000-fold moremethane than coke. In some embodiments of aspects provided herein, themethanation reaction forms at least about 10000-fold more methane thancoke. In some embodiments of aspects provided herein, the methanationreaction forms at least about 100000-fold more methane than coke. Insome embodiments of aspects provided herein, the method furthercomprises any two of (i), (ii) and (iii). In some embodiments of aspectsprovided herein, the method further comprises all of (i), (ii) and(iii). In some embodiments of aspects provided herein, C₅₊ compounds areremoved from the ETL effluent prior to performing the methanationreaction with the methanation catalyst. In some embodiments of aspectsprovided herein, C₄₊ compounds are removed from the ETL effluent priorto performing the methanation reaction with the methanation catalyst. Insome embodiments of aspects provided herein, C₃₊ compounds are removedfrom the ETL effluent prior to performing the methanation reaction withthe methanation catalyst.

An aspect of the present disclosure provides a method of producing aplurality of hydrocarbon products, comprising: (a) in an oxidativecoupling of methane (OCM) reactor, reacting methane and an oxidant in anOCM process to yield heat and an OCM product stream comprisinghydrocarbon compounds with two or more carbon atoms (C₂₊ compounds),including ethylene; (b) directing the OCM product stream from the OCMreactor to a post-bed cracking (PBC) unit downstream of the OCM reactor;(c) in the PBC unit, subjecting the OCM product stream to thermalcracking under conditions that are suitable to crack ethane to ethylene,wherein the thermal cracking is conducted at least in part with the heatfrom (a), thereby producing a PBC product stream comprising ethylene andhydrogen (H₂) at concentrations that are increased relative to therespective concentrations of ethylene and H₂ in the OCM product stream;(d) directing the PBC product stream from the PBC unit to anethylene-to-liquids (ETL) reactor downstream of the PBC unit, whereinthe ETL reactor converts the ethylene in the PBC product stream intohigher hydrocarbons.

An aspect of the present disclosure provides a method of producing aplurality of hydrocarbon products, comprising: directing ethylene andhydrogen (H₂) into an ethylene-to-liquids (ETL) reactor, wherein the ETLreactor is configured to convert hydrocarbon compounds with two or morecarbon atoms (C₂₊ compounds), including ethylene, into higherhydrocarbons; and in the ETL reactor, converting the ethylene intohigher hydrocarbons in the presence of the H₂, wherein the convertingresults in less coke formation than if the converting is conducted inthe absence of the H₂.

An aspect of the present disclosure provides a method of producing aplurality of hydrocarbon products, comprising: directing ethylene andwater (H₂O) into an ethylene-to-liquids (ETL) reactor, wherein the ETLreactor is configured to convert hydrocarbon compounds with two or morecarbon atoms (C₂₊ compounds), including ethylene, into higherhydrocarbons; and in an ethylene-to-liquids (ETL) reactor, convertingthe ethylene into higher hydrocarbons in the presence of the H₂O,wherein the converting results in less coke formation than if theconverting is conducted in the absence of the H₂O.

An aspect of the present disclosure provides a method of producing aplurality of hydrocarbon products, comprising: (a) introducing a feedstream comprising ethylene and ethane into an ethylene-to-liquids (ETL)reactor, wherein the ETL reactor is configured to convert hydrocarboncompounds with two or more carbon atoms (C₂₊ compounds) into higherhydrocarbons, and wherein the ethylene to ethane molar ratio in the feedstream is at least about 3:1 and (b) in the ETL reactor, converting theethylene into the higher hydrocarbons.

An aspect of the present disclosure provides a method of producing aplurality of hydrocarbon products, comprising: directing ethylene to anethylene-to-liquids (ETL) reactor, wherein the ETL reactor is configuredto convert hydrocarbon compounds with two or more carbon atoms (C₂₊compounds) into higher hydrocarbons; in the ETL reactor, converting theethylene into the higher hydrocarbons; and separating the higherhydrocarbons into at least two product streams, at least one of whichproduct streams is characterized by five or more characteristicsselected from the group consisting of: (a) no more than 1.30 vol %benzene; (b) no more than 50 vol % aromatics; (c) no more than 25 vol %olefins; (d) a motor octane number (MON) of at least 82; (e) a totaloctane number of at least 87; (f) a Reid vapor pressure (RVP) of no morethan 15 psi; (g) a 10% boiling point of no more than 70° C.; (h) a 50%boiling point of no more than 121° C.; (i) a 90% boiling point of nomore than 190° C.; (j) a final boiling point (FBP) of no more than 221°C.; and (k) an oxidative induction time of at least 240 minutes.

An aspect of the present disclosure provides a method of producing aplurality of hydrocarbon products, comprising: directing ethylene intoan ethylene-to-liquids (ETL) reactor, wherein the ETL reactor isconfigured to convert hydrocarbon compounds with two or more carbonatoms (C₂₊ compounds), including ethylene, into higher hydrocarbons; andin the ETL reactor, converting ethylene into higher hydrocarbon productsin an ETL product stream that comprises less than 60% water.

An aspect of the present disclosure provides a method of producing aplurality of hydrocarbon products, comprising: (a) directing ethyleneinto an ethylene-to-liquids (ETL) reactor, wherein the ETL reactorcomprises an ETL catalyst that is configured to convert hydrocarboncompounds with two or more carbon atoms (C₂₊ compounds), includingethylene, into higher hydrocarbons; (b) in the ETL reactor, convertingthe ethylene into higher hydrocarbons to provide an ETL product streamcomprising the higher hydrocarbons, and forming coke on the ETLcatalyst; (c) contacting the ETL catalyst with an oxidant to regeneratethe ETL catalyst by burning the coke on the ETL catalyst; and (d)repeating (b)-(c) for at least 20 cycles, wherein a composition of theETL product stream from a first cycle differs from a composition of theETL product stream from a twentieth cycle by no more than 0.1%.

An aspect of the present disclosure provides a method of producing aplurality of hydrocarbon products, comprising: (a) introducing a feedstream comprising hydrocarbons into a fluid catalytic cracking (FCC)reactor comprising an FCC catalyst, wherein the FCC catalyst isconfigured to crack the hydrocarbons into lower molecular weighthydrocarbons; (b) in the FCC reactor, (i) cracking the hydrocarbons intothe lower molecular weight hydrocarbons and (ii) generating coke on theFCC catalyst; (c) transferring at least a portion of the FCC catalystinto a regeneration unit and introducing an oxidant stream into theregeneration unit; (d) in the regeneration unit, burning the coke on theFCC catalyst in the presence of the oxidant stream, thereby regeneratingthe FCC catalyst and producing a flue gas stream comprising carbonmonoxide and/or carbon dioxide; (e) directing the flue gas stream into aheat exchanger to transfer heat from the flue gas stream to a firststream comprising ethane or propane; and (f) subjecting the first streamto thermal cracking under conditions that (i) crack the ethane toethylene and/or (ii) crack the propane to propene, wherein the thermalcracking is conducted at least in part with the heat from (e).

An aspect of the present disclosure provides a method of producing aplurality of hydrocarbon products, comprising: (a) in a first oxidativecoupling of methane (OCM) reactor, reacting methane and a first oxidantin an OCM process to yield a first OCM product stream comprisingunreacted methane and hydrocarbon compounds with two or more carbonatoms (C₂₊ compounds), including ethylene; (b) introducing the first OCMproduct stream into an ethylene-to-liquids (ETL) reactor that isconfigured to convert C₂₊ compounds into higher hydrocarbons; (c) in theETL reactor, converting at least a portion of the ethylene in the firstOCM product stream into higher hydrocarbons to provide an ETL productstream comprising the higher hydrocarbons and the unreacted methane; (d)introducing a second oxidant stream and at least a portion of the ETLproduct stream into a second OCM reactor; and (e) in the second OCMreactor, reacting the unreacted methane and the second oxidant inanother OCM process to yield a second OCM product stream comprising C₂₊compounds, including ethylene.

In some embodiments of aspects provided herein, the method furthercomprises, prior to the introducing of (e), removing at least a portionof the higher hydrocarbons from the ETL product stream.

An aspect of the present disclosure provides a method of producing aplurality of hydrocarbon products, comprising: (a) directing a feedstream comprising ethylene to an ethylene-to-liquids (ETL) reactor,wherein the ETL reactor is configured to convert hydrocarbon compoundswith two or more carbon atoms (C₂₊ compounds) into higher hydrocarbons;(b) converting the ethylene to an ETL product stream comprising thehigher hydrocarbons; (c) directing the ETL product stream to aseparations system and, in the separations system, separating the ETLproduct stream into a higher hydrocarbon stream and a light olefinstream comprising propylene and butene; (d) introducing the light olefinstream into an oligomerization reactor, wherein the oligomerizationreactor includes an oligomerization catalyst that oligomerizes C₂₊compounds into higher hydrocarbons; and (e) in the oligomerizationreactor, oligomerizing the propylene and butene in the light olefinstream to produce an oligomerization product stream comprisingoligomerization products of propylene and butene.

In some embodiments of aspects provided herein, the oligomerizationproduct stream comprises olefins with carbon numbers from 6 to 16. Insome embodiments of aspects provided herein, a temperature within theoligomerization reactor during the oligomerizing is from about 50° C. to200° C.

In some embodiments of aspects provided herein, the oligomerizationcatalyst comprises a solid acid catalyst. In some embodiments of aspectsprovided herein, the oligomerization reactor is of a form selected fromthe group consisting of a slurry bed reactor, a fixed bed reactor, atubular isothermal reactor, a moving bed reactor, and a fluidized bedreactor.

An aspect of the present disclosure provides a method of producing aplurality of hydrocarbon products, comprising: (a) in an oxidativecoupling of methane (OCM) reactor, reacting methane and an oxidant in anOCM process to yield an OCM product stream comprising unreacted methaneand hydrocarbon compounds with two or more carbon atoms (C₂₊ compounds)including ethylene, ethane, and propane; (b) introducing the OCM productstream into an ethylene-to-liquids (ETL) reactor, wherein the ETLreactor is configured to convert the unreacted methane and at least aportion of the C₂₊ compounds into aromatic hydrocarbons, and wherein theETL reactor comprises an ETL catalyst doped with one or more dopantsselected from the group consisting of molybdenum (Mo), gallium (Ga), andtungsten (W); and (c) in the ETL reactor, converting the unreactedmethane and the at least the portion of the C₂₊ compounds into anaromatic product stream comprising the aromatic hydrocarbons.

An aspect of the present disclosure provides a method of producing aplurality of hydrocarbon products, comprising: (a) directing hydrogen(H₂) and a low octane stream comprising n-hexane to an isomerizationreactor that is configured to isomerize n-hexane to i-hexane, whereinthe low octane stream is characterized by an octane number of no morethan 62; and (b) reacting the H₂ and the n-hexane to produce anisomerization product stream comprising i-hexane, wherein theisomerization product stream is characterized by an octane number of atleast 73.

An aspect of the present disclosure provides a method of producing aplurality of hydrocarbon products, comprising: (a) in a natural gasliquids (NGL) system, producing from natural gas an NGL product streamcomprising hydrocarbon compounds with four or more carbon atoms (C₄₊compounds), including butanes; (b) introducing the first NGL productstream into an isomerization reactor configured to isomerize the C₄₊compounds); and (c) in the isomerization reactor, isomerizing at least aportion of the C₄₊ compounds to form isomerization products, therebyproducing an isomerate stream comprising the isomerization products.

An aspect of the present disclosure provides a method of producing aplurality of hydrocarbon products, comprising: (a) in an oxidativecoupling of methane (OCM) reactor, reacting methane and an oxidant in anOCM process to yield an OCM product stream comprising unreacted methaneand hydrocarbon compounds comprising two or more carbon atoms (C₂₊compounds), including ethylene; (b) introducing the OCM product streaminto an ethylene-to-liquids (ETL) reactor that reacts the ethylene inthe OCM product stream to yield an ETL product stream higherhydrocarbons and unreacted methane; and (c) introducing the ETL productstream into at least one separation unit that separates the ETL productstream into a gas stream comprising the unreacted methane and at leastone product stream comprising hydrocarbon compounds with at least 3, 4,or 5 carbon atoms.

In some embodiments of aspects provided herein, the methane is suppliedat least in part from a natural gas pipeline, and wherein the methodfurther comprises outputting the gas stream to the natural gas pipeline.In some embodiments of aspects provided herein, the methane is suppliedat least in part from a cryogenic separations system, and wherein themethod further comprises directing the gas stream to a re-compressorunit. In some embodiments of aspects provided herein, the methane issupplied at least in part from a cryogenic separations system, andwherein the method further comprises compressing the gas stream in acompressor to produce a compressed stream and directing the compressedstream to the cryogenic separations unit. In some embodiments of aspectsprovided herein, the methane is supplied at least in part from acryogenic separations unit, and the method further comprises:compressing the gas stream in a compressor to produce a compressedstream; directing the compressed stream to the cryogenic separationsunit; in the cryogenic separations unit, removing any C₂₊ compounds fromthe gas stream along a C₂₊ product stream; and optionally directing thegas stream to a re-compressor unit.

An aspect of the present disclosure provides a method of producing aplurality of hydrocarbon products including hydrocarbon compounds withtwo carbon atoms (C₂ compounds), hydrocarbon compounds with three carbonatoms (C₃ compounds), hydrocarbon compounds with four carbon atoms (C₄compounds), and hydrocarbon compounds with five or more carbon atoms(C₅₊ compounds), comprising: (a) introducing a natural gas streamcomprising methane into a gas treatment system and, in the gas treatmentsystem, removing from the natural gas stream at least one of mercury,water, and acid gases; (b) directing the natural gas stream from the gastreatment system into a natural gas liquids (NGL) extraction system thatproduces from the natural gas stream a first stream comprising methaneand a second stream comprising C₂ compounds, C₃ compounds, C₄ compounds,and C₅₊ compounds; (c) directing a first portion of the first streaminto a liquefaction unit, and in the liquefaction unit, producing liquidnatural gas from the first portion of the first stream; (d) directingthe second stream into an NGL fractionation system that separates thesecond stream into at least (i) a C₂-C₃ stream comprising C₂ compoundsand C₃ compounds, (ii) a C₄ stream comprising C₄ compounds, and (iii) aC₅₊ stream comprising C₅₊ compounds; (e) directing a second portion ofthe first stream, the C₂-C₃ stream, and an oxidant into an oxidativecoupling of methane (OCM) system that converts the methane in the secondportion of the first stream in an OCM process to yield an OCM productstream including ethylene; (f) directing the OCM product stream into anethylene-to-liquids (ETL) reactor that converts the ethylene in the OCMproduct stream into the higher hydrocarbons, thereby forming an ETLproduct stream comprising C₂ compounds, C₃ compounds, C₄ compounds, andC₅₊ compounds; and (g) directing the ETL product stream into the NGLextraction system.

In some embodiments of aspects provided herein, the method furthercomprises, prior to the directing of (b), directing the natural gasstream from the gas treatment system into a pre-cooling system, and, inthe pre-cooling system, removing a first fuel gas stream comprisingmethane from the natural gas stream. In some embodiments of aspectsprovided herein, the method further comprises directing the liquidnatural gas stream into a nitrogen rejection unit, and, in the nitrogenrejection unit, removing a stream comprising nitrogen from the liquidnatural gas stream.

An aspect of the present disclosure provides a method of producing aplurality of hydrocarbon products including hydrocarbon compounds withtwo carbon atoms (C₂ compounds), hydrocarbon compounds with three carbonatoms (C₃ compounds), hydrocarbon compounds with four carbon atoms (C₄compounds), and hydrocarbon compounds with five or more carbon atoms(C₅₊ compounds), comprising: (a) directing a natural gas stream into anatural gas liquids (NGL) extraction system that produces from thenatural gas stream a first stream comprising methane and a second streamcomprising C₂ compounds, C₃ compounds, C₄ compounds, and C₅₊ compounds;(b) removing a first portion of the first stream as a pipeline gasproduct stream; (c) directing the second stream into an NGLfractionation system that separates the second stream into at least (i)a C₂-C₃ stream comprising C₂ compounds and C₃ compounds, (ii) a C₄stream comprising C₄ compounds, and (iii) a C₅₊ stream comprising C₅+compounds; (d) directing a second portion of the first stream, the C₂-C₃stream, and an oxidant into an oxidative coupling of methane (OCM)system that converts the methane in the second portion of the firststream in an OCM process to yield an OCM product stream includingethylene; (e) directing the OCM product stream into anethylene-to-liquids (ETL) reactor that converts the ethylene in the OCMproduct stream into an ETL product stream comprising C₂ compounds, C₃compounds, C₄ compounds, and C₅+ compounds; and (f) directing the ETLproduct stream into the NGL extraction system.

An aspect of the present disclosure provides a method of producing aplurality of hydrocarbon products including hydrocarbon compounds withtwo carbon atoms (C₂ compounds”), hydrocarbon compounds with threecarbon atoms (C₃ compounds), hydrocarbon compounds with four carbonatoms (C₄ compounds), and hydrocarbon compounds with five or more carbonatoms (C₅₊ compounds), comprising: (a) introducing a first natural gasstream comprising methane into a gas treatment system that removes fromthe first natural gas stream at least one of mercury, water, and acidgases; (b) introducing a second natural gas stream comprising methaneinto a gas conditioning system that removes from the second natural gasstream at least one sulfur compound; (c) directing the first natural gasstream from the gas treatment system and a first portion of the secondnatural gas stream from the gas conditioning system into a natural gasliquids (NGL) extraction system that produces from the first natural gasstream and the first portion of the second natural gas stream (i) afirst stream comprising methane, (ii) a second stream comprising C₂compounds, and (iii) a third stream comprising C₂ compounds, C₃compounds, C₄ compounds, and C₅₊ compounds, wherein a portion of thefirst stream is removed as a pipeline gas product stream; (d) directingthe third stream into an NGL fractionation system that separates thethird stream into at least (i) a C₂ stream comprising C₂ compounds, (ii)a C₃-C₄ stream comprising C₃ compounds and C₄ compounds, and (iii) a C₅₊stream comprising C₅₊ compounds; (e) directing a second portion of thesecond natural gas stream from the gas conditioning system, the secondstream from the NGL extraction system, the C₂ stream from the NGLfractionation system, and an oxidant into an oxidative coupling ofmethane (OCM) reactor that converts methane at least some of the streamsin an OCM process to yield an OCM product stream including ethylene; (f)directing the OCM product stream into an ethylene-to-liquids (ETL)reactor that converts the ethylene in the OCM product stream into an ETLproduct stream comprising C₂ compounds, C₃ compounds, C₄ compounds, andC₅₊ compounds; and (g) directing the ETL product stream into the NGLextraction system.

An aspect of the present disclosure provides a method of producing aplurality of hydrocarbon products including hydrocarbon compounds withtwo carbon atoms (C₂ compounds), hydrocarbon compounds with three carbonatoms (C₃ compounds), hydrocarbon compounds with four carbon atoms (C₄compounds), and hydrocarbon compounds with five or more carbon atoms(C₅₊ compounds), comprising: (a) directing a first stream includingethylene from a refinery gas plant into an ethylene-to-liquids (ETL)reactor that converts the ethylene into an ETL product stream comprisingC₂ compounds, C₃ compounds, C₄ compounds, and C₅₊ compounds; (b)directing the ETL product stream into a separations system thatseparates the ETL product stream into at least (i) a fuel gas streamcomprising methane, (ii) a C₂ stream comprising C₂ compounds, and (iii)a C₃ stream comprising C₃ compounds; (c) using a heat exchanger,transferring heat from the C₂ stream to a first stream comprising ethaneand/or propane; and (d) subjecting the first stream to thermal crackingunder conditions that crack the ethane to ethylene and/or the propane topropene, wherein the thermal cracking is conducted at least in part withthe heat from (c).

In some embodiments of aspects provided herein, the method furthercomprises directing the C₂ stream from the heat exchanger to the ETLreactor.

An aspect of the present disclosure provides a method of producing aplurality of hydrocarbon products including hydrocarbon compounds withtwo carbon atoms (C₂ compounds), hydrocarbon compounds with three carbonatoms (C₃ compounds), hydrocarbon compounds with four carbon atoms (C₄compounds), and hydrocarbon compounds with five or more carbon atoms(C₅₊ compounds), comprising: (a) directing a first stream includingethylene from a refinery gas plant into a demethanizer that removes afirst methane stream including methane from the first stream, whereinthe first stream is subjected to sulfur removal prior to being directedto the demethanizer; (b) directing the first methane stream, a secondmethane stream comprising methane, and an oxidant into an oxidativecoupling of methane (OCM) system that converts methane in the in an OCMprocess to yield an OCM product stream including ethylene; (c) directingthe first stream and the OCM product stream into an ethylene-to-liquids(ETL) that converts the ethylene in the OCM product stream into an ETLproduct stream comprising C₂ compounds, C₃ compounds, C₄ compounds, andC₅₊ compounds; (d) directing the ETL product stream into a separationssystem that separates the ETL product stream into at least streamscomprising a C₂-C₃ stream comprising C₂ compounds and C₃ compounds; and(e) using a heat exchanger, transferring heat from the C₂-C₃ stream to asecond stream comprising ethane and/or propane; and (f) subjecting thesecond stream to thermal cracking under conditions that crack the ethaneto ethylene and/or the propane to propene, wherein the thermal crackingis conducted at least in part with the heat from (e).

In some embodiments of aspects provided herein, the method furthercomprises directing at least a portion of the C₂-C₃ stream from the heatexchanger to the OCM reactor system. In some embodiments of aspectsprovided herein, the method further comprises directing at least aportion of the C₂-C₃ stream from the heat exchanger to the ETL reactor.

An aspect of the present disclosure provides a method of producing aplurality of hydrocarbon products including hydrocarbon compounds withtwo or more carbon atoms (C₂₊ compounds), comprising: (a) directingmethane and an oxidant to an oxidative coupling of methane (OCM) reactorthat is upstream of a post-bed cracking (PBC) unit, wherein the OCMreactor is configured to facilitate an OCM reaction using the methaneand the oxidant to generate the C₂₊ compounds including ethylene and oneor more alkanes, and wherein the PBC unit is configured to convert theone or more alkanes, including ethane, to one or more alkenes, includingethylene; (b) in the OCM reactor, reacting the methane and the oxidantin the OCM reaction to generate an OCM product stream and heat, whereinthe OCM product stream comprises ethylene and one or more alkanes; (c)directing the OCM product stream to the PBC unit; (d) in the PBC unit,subjecting the OCM product stream to thermal cracking under conditionsthat crack ethane to ethylene, wherein the thermal cracking is conductedat least in part with the heat from (c), thereby producing a PBC productstream comprising ethylene; (e) directing the PBC product stream to aseparations module, and, in the separations module, separating ethanefrom the PBC product stream to generate an ethane stream; and (f)directing the ethane stream to the PBC unit.

Additional aspects and advantages of the present disclosure will becomereadily apparent to those skilled in this art from the followingdetailed description, wherein only illustrative embodiments of thepresent disclosure are shown and described. As will be realized, thepresent disclosure is capable of other and different embodiments, andits several details are capable of modifications in various obviousrespects, all without departing from the disclosure. Accordingly, thedrawings and description are to be regarded as illustrative in nature,and not as restrictive.

INCORPORATION BY REFERENCE

All publications, patents, and patent applications mentioned in thisspecification are herein incorporated by reference to the same extent asif each individual publication, patent, or patent application wasspecifically and individually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe appended claims. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings or figures (also “FIG.” and “FIGS.” herein), ofwhich:

FIG. 1 shows an oxidative coupling of methane (OCM) reactor system;

FIG. 2 schematically illustrates differentially cooled tubular reactorsystems;

FIG. 3 schematically illustrates a reactor system with two or moretubular reactors;

FIG. 4A schematically illustrates an alternative approach for varyingreactor volumes in order to vary residence time of reactants in acatalyst bed;

FIG. 4B schematically illustrates an exemplary fluidized bed reactor;

FIG. 4C schematically illustrates exemplary moving bed, fluidized bed,and slurry bed reactors;

FIG. 5 is an example of the manner in which product distribution canchange over time for an ETL catalyst;

FIG. 6 schematically illustrates an ethylene-to-liquids (ETL) reactorsystem with process inlet and recycle stream combining to form a reactorinlet process stream;

FIG. 7A shows liquid phase hydrocarbon yield as a function of C₂H₄conversion by using a single pass reactor;

FIG. 7B shows liquid phase hydrocarbon yield as a function of C₂H₄conversion by using a reactor with 5:1 recycle:fresh ratio;

FIG. 8 is a plot showing increasing C₅₊ yield (liquid condensed at about0° C.) with increasing recycle reaction conditions;

FIG. 9 shows an example of a pressure swing adsorption (PSA) unit;

FIG. 10 schematically illustrates an integrated OCM system withintegrated separations system;

FIG. 11 shows an example of NGL extraction in a liquefied natural gas(LNG) facility;

FIG. 12 shows an integrated OCM-ETL system for use in LNG production;

FIG. 13 shows the system of FIG. 12 that has been modified for use witha diluted C1 (methane) fuel gas stream;

FIG. 14 shows an example OCM-ETL system comprising OCM and ETLsub-systems, and a separations sub-system downstream of the ETLsub-system;

FIG. 15 shows an OCM-ETL system comprising OCM and ETL sub-systems, anda cryogenic cold box downstream of the ETL sub-system;

FIG. 16 shows another OCM-ETL in an alternative configuration to thatshown in FIG. 14;

FIG. 17 show examples of OCM-ETL midstream integration;

FIG. 18 show examples of OCM-ETL midstream integration;

FIG. 19 shows OCM-ETL systems with various skimmer and recycleconfigurations.

FIG. 20 shows an example of ETL integration in a refinery;

FIG. 21 shows another example of ETL integration in a refinery;

FIG. 22 shows another example of ETL integration in a refinery;

FIG. 23A schematically illustrates a natural gas liquids (NGL) system;FIG. 23B schematically illustrates the NGL process of FIG. 23Aretrofitted with an OCM and ethylene to liquids system;

FIG. 24 schematically illustrates an oxidative coupling of methane (OCM)olefins to liquids process integrated in an NGL system, employing air inan OCM process;

FIG. 25 schematically illustrates an OCM-ETL integration with anexisting NGL system, employing oxygen (O₂) in an OCM process;

FIG. 26 schematically illustrates a methanation system;

FIG. 27 shows an example of methanation systems for OCM and ETL;

FIG. 28 shows a separation system that may be employed for use withsystems and methods of the present disclosure;

FIG. 29 shows another separation system that may be employed for usewith systems and methods of the present disclosure;

FIG. 30 shows another separation system that may be employed for usewith systems and methods of the present disclosure;

FIG. 31 shows another separation system that may be employed for usewith systems and methods of the present disclosure;

FIG. 32 shows an example of an ethane skimmer implementation of OCM andETL; and

FIG. 33 shows a computer system that is programmed or otherwiseconfigured to regulate OCM reactions;

FIG. 34 schematically illustrates a process flow for conversion ofethylene to higher liquid hydrocarbons for use in, e.g., fuels and fuelblendstocks;

FIG. 35 shows a graph of exemplary product compositions over time onstream;

FIGS. 36A-36E shows graphs of ETL products with various feedstocks. FIG.36A shows a graph of ETL product with ethylene feedstock; FIG. 36B showsa graph of ETL product with propylene feedstock; FIG. 36C shows a graphof ETL product with butylene feedstock; FIG. 36D shows a graph of ETLproduct with 50:50 ethylene/propylene feedstock; and FIG. 36E shows agraph of ETL product with 50:50 ethylene/butylene feedstock;

FIG. 37 shows a graph of product composition versus catalyst bed peaktemperature;

FIG. 38 shows a graph of ETL product divided into a gasoline fractionand a jet fraction;

FIG. 39 shows a graph of crush strength for various catalystformulations;

FIG. 40 shows a graph comparing catalyst aging under commercial andaccelerated conditions; and

FIG. 41 shows a graph comparing product composition over catalystregeneration cycles.

DETAILED DESCRIPTION

While various embodiments of the invention have been shown and describedherein, it will be obvious to those skilled in the art that suchembodiments are provided by way of example only. Numerous variations,changes, and substitutions may occur to those skilled in the art withoutdeparting from the invention. It should be understood that variousalternatives to the embodiments of the invention described herein may beemployed.

Unless the context requires otherwise, throughout the specification andclaims which follow, the word “comprise” and variations thereof, suchas, “comprises” and “comprising” are to be construed in an open,inclusive sense, that is, as “including, but not limited to.” Further,headings provided herein are for convenience only and do not interpretthe scope or meaning of the claimed invention.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure or characteristicdescribed in connection with the embodiment is included in at least oneembodiment. Thus, the appearances of the phrases “in one embodiment” or“in an embodiment” in various places throughout this specification arenot necessarily all referring to the same embodiment. Furthermore, theparticular features, structures, or characteristics may be combined inany suitable manner in one or more embodiments. Also, as used in thisspecification and the appended claims, the singular forms “a,” “an,” and“the” include plural referents unless the content clearly dictatesotherwise. It should also be noted that the term “or” is generallyemployed in its sense including “and/or” unless the content clearlydictates otherwise.

The term “OCM process,” as used herein, generally refers to a processthat employs or substantially employs an oxidative coupling of methane(OCM) reaction. An OCM reaction can include the oxidation of methane toa higher hydrocarbon (e.g., higher molecular weight hydrocarbon orhigher chain hydrocarbon) and water, and involves an exothermicreaction. In an OCM reaction, methane can be partially oxidized to oneor more C₂₊ compounds, such as ethylene, propylene, butylenes, etc. Inan example, an OCM reaction is 2CH₄+O₂→C₂H₄+2H₂O. An OCM reaction canyield C₂₊ compounds. An OCM reaction can be facilitated by a catalyst,such as a heterogeneous catalyst. Additional by-products of OCMreactions can include CO, CO₂, H₂, as well as hydrocarbons, such as, forexample, ethane, propane, propene, butane, butene, and the like.

The term “non-OCM process,” as used herein, generally refers to aprocess that does not employ or substantially employ an oxidativecoupling of methane reaction. Examples of processes that may be non-OCMprocesses include non-OCM hydrocarbon processes, such as, for example,non-OCM processes employed in hydrocarbon processing in oil refineries,a natural gas liquids separations processes, steam cracking of ethane,steam cracking or naphtha, Fischer-Tropsch processes, and the like.

The term “ethylene-to-liquids” (ETL), as used herein, generally refersto any device, system, method (or process) that can convert an olefin(e.g., ethylene) to higher molecular weight hydrocarbons, which can bein liquid form.

The term “non-ETL process,” as used herein, generally refers to aprocess that does not employ or substantially employ the conversion ofan olefin to a higher molecular weight hydrocarbon througholigomerization. Examples of processes that may be non-ETL processesinclude processes employed in hydrocarbon processing in oil refineries,a natural gas liquids separations processes, steam cracking of ethane,steam cracking or naphtha, Fischer-Tropsch processes, and the like.

The terms “C₂₊” and “C₂₊ compound,” as used herein, generally refer to acompound comprising two or more carbon atoms, e.g., C₂, C₃ etc. C₂₊compounds include, without limitation, alkanes, alkenes, alkynes andaromatics containing two or more carbon atoms. In some cases, C₂₊compounds include aldehydes, ketones, esters and carboxylic acids.Examples of C₂₊ compounds include ethane, ethene, acetylene, propane,propene, butane, butene, etc.

The term “non-C₂₊ impurities,” as used herein, generally refers tomaterial that does not include C₂₊ compounds. Examples of non-C₂₊impurities, which may be found in certain OCM reaction product streams,include nitrogen (N₂), oxygen (O₂), water (H₂O), argon (Ar), hydrogen(H₂) carbon monoxide (CO), carbon dioxide (CO₂) and methane (CH₄).

The term “weight hourly space velocity” (WHSV), as used herein,generally refers to the mass flow rate of olefins in a feed divided bythe mass of a catalyst, which can have units of inverse time (e.g.,hr⁻¹).

The term “slate,” as used herein, generally refers to distribution, suchas product distribution.

The term “oligomerization,” as used herein, generally refers to areaction in which hydrocarbons are combined to form larger chainhydrocarbons.

The term “greenfield,” as used herein, generally refers to an investmentin a manufacturing, office, industrial or other physicalcommerce-related structure or group of structures in an area where noprevious facilities exist or have existed.

The term “brownfield,” as used herein, generally refers to an investmentat a site that was previously used for business purposes, such as asteel mill or an oil refinery, but is subsequently expanded or upgradedto achieve a return.

The term “catalyst,” as used herein, generally refers to a substancethat alters the rate of a chemical reaction. A catalyst may eitherincrease the chemical reaction rate (i.e. a “positive catalyst”) ordecrease the reaction rate (i.e. a “negative catalyst”). A catalyst canbe a heterogeneous catalyst. Catalysts can participate in a reaction ina cyclic fashion such that the catalyst is cyclically regenerated.“Catalytic” generally means having the properties of a catalyst.

The term “nanowire,” as used herein, generally refers to a nanowirestructure having at least one diameter on the order of nanometers (e.g.between about 1 and 100 nanometers) and an aspect ratio greater than10:1. The “aspect ratio” of a nanowire is the ratio of the actual length(L) of the nanowire to the diameter (D) of the nanowire. Aspect ratio isexpressed as L:D.

The term “polycrystalline nanowire,” as used herein, generally refers toa nanowire having multiple crystal domains. Polycrystalline nanowiresgenerally have different morphologies (e.g. bent vs. straight) ascompared to the corresponding “single-crystalline” nanowires.

The term “effective length” of a nanowire, as used herein, generallyrefers to the shortest distance between the two distal ends of ananowire as measured by transmission electron microscopy (TEM) in brightfield mode at 5 kilo electron volt (keV). “Average effective length”refers to the average of the effective lengths of individual nanowireswithin a plurality of nanowires.

The term “actual length” of a nanowire, as used herein, generally refersto the distance between the two distal ends of a nanowire as tracedthrough the backbone of the nanowire as measured by TEM in bright fieldmode at 5 keV. “Average actual length” refers to the average of theactual lengths of individual nanowires within a plurality of nanowires.

A “diameter” of a nanowire can be measured in an axis perpendicular tothe axis of the nanowire's actual length (i.e. perpendicular to thenanowires backbone). The diameter of a nanowire will vary from narrow towide as measured at different points along the nanowire backbone. Asused herein, the diameter of a nanowire is the most prevalent (i.e. themode) diameter.

A “ratio of effective length to actual length” can be determined bydividing the effective length by the actual length. A nanowire having a“bent morphology” can have a ratio of effective length to actual lengthof less than one as described in more detail herein. A straight nanowirewill have a ratio of effective length to actual length equal to one.

The term “inorganic,” as used herein, generally refers to a substancecomprising a metal element or semi-metal element. In certainembodiments, inorganic refers to a substance comprising a metal element.An inorganic compound can contain one or more metals in its elementalstate, or more typically, a compound formed by a metal ion (M^(n+),wherein n 1, 2, 3, 4, 5, 6 or 7) and an anion (X^(m−), m is 1, 2, 3 or4), which balance and neutralize the positive charges of the metal ionthrough electrostatic interactions. Non-limiting examples of inorganiccompounds include oxides, hydroxides, halides, nitrates, sulfates,carbonates, phosphates, acetates, oxalates, and combinations thereof, ofmetal elements. Other non-limiting examples of inorganic compoundsinclude Li₂CO₃, Li₂PO₄, LiOH, Li₂O, LiCl, LiBr, LiI, Li₂C₂O₄, Li₂SO₄,Na₂CO₃, Na₂PO₄, NaOH, Na₂O, NaCl, NaBr, NaI, Na₂C₂O₄, Na₂SO₄, K₂CO₃,K₂PO₄, KOH, K₂O, KCl, KBr, KI, K₂C₂O₄, K₂SO₄, Cs₂CO₃, CsPO₄, CsOH, Cs₂O,CsCl, CsBr, CsI, CsC₂O₄, CsSO₄, Be(OH)₂, BeCO₃, BePO₄, BeO, BeCl₂,BeBr₂, BeI₂, BeC₂O₄. BeSO₄, Mg(OH)₂, MgCO₃, MgPO₄, MgO, MgCl₂, MgBr₂,MgI₂, MgC₂O₄. MgSO₄, Ca(OH)₂, CaO, CaCO₃, CaPO₄, CaCl₂, CaBr₂, CaI₂,Ca(OH)₂, CaC₂O₄, CaSO₄, Y₂O₃, Y₂(CO₃)₃, Y₂(PO₄)₃, Y(OH)₃, YCl₃, YBr₃,YI₃, Y₂(C₂O₄)₃, Y₂(SO₄)₃, Zr(OH)₄, Zr(CO₃)₂, Zr(PO₄)₂, ZrO(OH)₂, ZrO2,ZrCl₄, ZrBr₄, ZrI₄, Zr(C₂O₄)₂, Zr(SO₄)₂, Ti(OH)₄, TiO(OH)₂, Ti(CO₃)₂,Ti(PO₄)₂, TiO2, TiCl₄, TiBr₄, TiI₄, Ti(C₂O₄)₂, Ti(SO₄)₂, BaO, Ba(OH)₂,BaCO₃, BaPO₄, BaCl₂, BaBr₂, BaI₂, BaC₂O₄, BaSO₄, La(OH)₃, La₂(CO₃)₃,La₂(PO₄)₃, La₂O₃, LaCl₃, LaBr₃, LaI₃, La₂(C₂O₄)₃, La₂(SO₄)₃, Ce(OH)₄,Ce(CO₃)₂, Ce(PO₄)₂, CeO₂, Ce₂O₃, CeCl₄, CeBr₄, CeI₄, Ce(C₂O₄)₂,Ce(SO₄)₂, ThO₂, Th(CO₃)₂, Th(PO₄)₂, ThCl₄, ThBr₄, ThI₄, Th(OH)₄,Th(C₂O₄)₂, Th(SO₄)₂, Sr(OH)₂, SrCO₃, SrPO₄, SrO, SrCl₂, SrBr₂, SrI₂,SrC₂O₄, SrSO₄, Sm₂O₃, Sm₂(CO₃)₃, Sm₂(PO₄)₃, SmCl₃, SmBr₃, SmI₃, Sm(OH)₃,Sm₂(CO3)₃, Sm₂(C₂O₃)₃, Sm₂(SO₄)₃, LiCa₂Bi₃O₄Cl₆, Na₂WO₄, K/SrCoO₃,K/Na/SrCoO₃, Li/SrCoO₃, SrCoO₃, molybdenum oxides, molybdenumhydroxides, molybdenum carbonates, molybdenum phosphates, molybdenumchlorides, molybdenum bromides, molybdenum iodides, molybdenum oxalates,molybdenum sulfates, manganese oxides, manganese chlorides, manganesebromides, manganese iodides, manganese hydroxides, manganese oxalates,manganese sulfates, manganese tungstates, vanadium oxides, vanadiumcarbonates, vanadium phosphates, vanadium chlorides, vanadium bromides,vanadium iodides, vanadium hydroxides, vanadium oxalates, vanadiumsulfates, tungsten oxides, tungsten carbonates, tungsten phosphates,tungsten chlorides, tungsten bromides, tungsten iodides, tungstenhydroxides, tungsten oxalates, tungsten sulfates, neodymium oxides,neodymium carbonates, neodymium phosphates, neodymium chlorides,neodymium bromides, neodymium iodides, neodymium hydroxides, neodymiumoxalates, neodymium sulfates, europium oxides, europium carbonates,europium phosphates, europium chlorides, europium bromides, europiumiodides, europium hydroxides, europium oxalates, europium sulfatesrhenium oxides, rhenium carbonates, rhenium phosphates, rheniumchlorides, rhenium bromides, rhenium iodides, rhenium hydroxides,rhenium oxalates, rhenium sulfates, chromium oxides, chromiumcarbonates, chromium phosphates, chromium chlorides, chromium bromides,chromium iodides, chromium hydroxides, chromium oxalates, chromiumsulfates, potassium molybdenum oxides and the like.

The term “salt,” as used herein, generally refers to a compoundcomprising negative and positive ions. Salts are generally comprised ofcations and counter ions. Under appropriate conditions, e.g., thesolution also comprises a template, the metal ion (M^(n+)) and the anion(X^(m−)) bind to the template to induce nucleation and growth of ananowire of M_(m)X_(n) on the template. “Anion precursor” thus is acompound that comprises an anion and a cationic counter ion, whichallows the anion (X^(m−)) to dissociate from the cationic counter ion ina solution. Specific examples of the metal salt and anion precursors aredescribed in further detail herein.

The term “oxide,” as used herein, generally refers to a metal orsemiconductor compound comprising oxygen. Examples of oxides include,but are not limited to, metal oxides (M_(x)O_(y)), metal oxyhalides(M_(x)O_(y)X_(z)), metal hydroxyhalides (M_(x)OH_(y)X_(z)), metaloxynitrates (M_(x)O_(y)(NO₃)_(z)), metal phosphates (M_(x)(PO₄)_(y)),metal oxycarbonates (M_(x)O_(y)(CO₃)_(z)), metal carbonates(M_(x)(CO₃)_(z)), metal sulfates (M_(x)(SO₄)_(z)), metal oxysulfates(M_(x)O_(y)(SO₄)_(z)), metal phosphates (M_(x)(PO₄)_(z)), metal acetates(M_(x)(CH₃CO₂)_(z)), metal oxalates (M_(x)(C₂O₄)_(z)), metaloxyhydroxides (M_(x)O_(y)(OH)_(z)), metal hydroxides (M_(x)(OH)_(z)),hydrated metal oxides (M_(x)O_(y)).(H₂O)_(z) and the like, wherein X isindependently, at each occurrence, fluoro, chloro, bromo or iodo, and x,y and z are independently numbers from 1 to 100.

The term “mixed oxide” or “mixed metal oxide,” as used herein, generallyrefers to a compound comprising two or more metals and oxygen (i.e.,M1_(x)M2_(y)O_(z), wherein M1 and M2 are the same or different metalelements, O is oxygen and x, y and z are numbers from 1 to 100). A mixedoxide may comprise metal elements in various oxidation states and maycomprise more than one type of metal element. For example, a mixed oxideof manganese and magnesium comprises oxidized forms of magnesium andmanganese. Each individual manganese and magnesium atom may or may nothave the same oxidation state. Mixed oxides comprising 2, 3, 4, 5, 6 ormore metal elements can be represented in an analogous manner. Mixedoxides also include oxy-hydroxides (e.g., M_(x)O_(y)OH_(z), wherein M isa metal element, O is oxygen, x, y and z are numbers from 1 to 100 andOH is hydroxy). Mixed oxides may be represented herein as M1-M2, whereinM1 and M2 are each independently a metal element.

The term “crystal domain,” as used herein, generally refers to acontinuous region over which a substance is crystalline.

The term “single-crystalline” or “mono-crystalline,” as used herein,generally refers to a material (e.g., nanowire) having a single crystaldomain.

The term “dopant” or “doping agent,” as used herein, generally refers toa material (e.g., impurity) added to or incorporated within a catalystto alter (e.g., optimize) catalytic performance (e.g. increase ordecrease catalytic activity). As compared to the undoped catalyst, adoped catalyst may increase or decrease the selectivity, conversion,and/or yield of a reaction catalyzed by the catalyst.

The term “OCM catalyst,” as used herein, generally refers to a catalystcapable of catalyzing an OCM reaction.

“Group 1” elements include lithium (Li), sodium (Na), potassium (K),rubidium (Rb), cesium (Cs), and francium (Fr).

“Group 2” elements include beryllium (Be), magnesium (Mg), calcium (Ca),strontium (Sr), barium (Ba), and radium (Ra).

“Group 3” elements include scandium (Sc) and yttrium (Y).

“Group 4” elements include titanium (Ti), zirconium (Zr), halfnium (Hf),and rutherfordium (Rf).

“Group 5” elements include vanadium (V), niobium (Nb), tantalum (Ta),and dubnium (Db).

“Group 6” elements include chromium (Cr), molybdenum (Mo), tungsten (W),and seaborgium (Sg).

“Group 7” elements include manganese (Mn), technetium (Tc), rhenium(Re), and bohrium (Bh).

“Group 8” elements include iron (Fe), ruthenium (Ru), osmium (Os), andhassium (Hs).

“Group 9” elements include cobalt (Co), rhodium (Rh), iridium (Ir), andmeitnerium (Mt).

“Group 10” elements include nickel (Ni), palladium (Pd), platinum (Pt)and darmistadium (Ds).

“Group 11” elements include copper (Cu), silver (Ag), gold (Au), androentgenium (Rg).

“Group 12” elements include zinc (Zn), cadmium (Cd), mercury (Hg), andcopernicium (Cn).

“Lanthanides” include lanthanum (La), cerium (Ce), praseodymium (Pr),neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu),gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium(Er), thulium (Tm), yitterbium (Yb), and lutetium (Lu).

“Actinides” include actinium (Ac), thorium (Th), protactinium (Pa),uranium (U), neptunium (Np), plutonium (Pu), americium (Am), curium(Cm), berklelium (Bk), californium (Cf), einsteinium (Es), fermium (Fm),mendelevium (Md), nobelium (No), and lawrencium (Lr).

“Rare earth” elements include Group 3, lanthanides and actinides.

“Metal element” or “metal” is any element, except hydrogen, selectedfrom Groups 1 through 12, lanthanides, actinides, aluminum (Al), gallium(Ga), indium (In), tin (Sn), thallium (Tl), lead (Pb), and bismuth (Bi).Metal elements include metal elements in their elemental form as well asmetal elements in an oxidized or reduced state, for example, when ametal element is combined with other elements in the form of compoundscomprising metal elements. For example, metal elements can be in theform of hydrates, salts, oxides, as well as various polymorphs thereof,and the like.

The term “semi-metal element,” as used herein, generally refers to anelement selected from boron (B), silicon (Si), germanium (Ge), arsenic(As), antimony (Sb), tellurium (Te), and polonium (Po).

The term “non-metal element,” as used herein, generally refers to anelement selected from carbon (C), nitrogen (N), oxygen (O), fluorine(F), phosphorus (P), sulfur (S), chlorine (Cl), selenium (Se), bromine(Br), iodine (I), and astatine (At).

The term “higher hydrocarbon,” as used herein, generally refers to ahigher molecular weight and/or higher chain hydrocarbon. A higherhydrocarbon can have a higher molecular weight and/or carbon contentthat is higher or larger relative to starting material in a givenprocess (e.g., OCM or ETL). A higher hydrocarbon can be a highermolecular weight and/or chain hydrocarbon product that is generated inan OCM or ETL process. For example, ethylene is a higher hydrocarbonproduct relative to methane in an OCM process. As another example, a C₃₊hydrocarbon is a higher hydrocarbon relative to ethylene in an ETLprocess. As another example, a C₅₊ hydrocarbon is a higher hydrocarbonrelative to ethylene in an ETL process. In some cases, a higherhydrocarbon is a higher molecular weight hydrocarbon.

The present disclosure is generally directed to processes and systemsfor use in the production of hydrocarbon compositions. These processesand systems may be characterized in that they derive the hydrocarboncompositions from ethylene that is, in turn, derived from methane, forexample as is present in natural gas. The disclosed processes andsystems are typically further characterized in that the process forconversion of methane to ethylene is integrated with one or moreprocesses or systems for converting ethylene to one or more higherhydrocarbon products, which, in some embodiments, comprise liquidhydrocarbon compositions. By converting the methane present in naturalgas to a liquid material, one can eliminate one of the key hurdlesinvolved in exploitation of the world's vast natural gas reserves,namely transportation. In particular, exploitation of natural gasresources traditionally has required extensive, and costly pipelineinfrastructures for movement of gas from the wellhead to its ultimatedestination. By converting that gas to a liquid material, moreconventional transportation systems become available, such as truck,rail car, tanker ship, and the like.

In some embodiments, processes and systems provided herein includemultiple (i.e., two or more) ethylene conversion process pathsintegrated into the overall processes or systems, in order to producemultiple different higher hydrocarbon compositions from the singleoriginal methane source. Further advantages are gained by providing theintegration of these multiple conversion processes or systems in aswitchable or selectable architecture whereby a portion or all of theethylene containing product of the methane to ethylene conversion systemis selectively directed to one or more different process paths, forexample two, three, four, five or more different process paths to yieldas many different products. This overall process flow is schematicallyillustrated in FIG. 1. As shown, an oxidative coupling of methane(“OCM”) reactor system 100 is schematically illustrated that includes anOCM reactor train 102 coupled to a OCM product gas separation train 104,such as a cryogenic separation system. The ethylene rich effluent (shownas arrow 106) from the separation train 104 is shown being routed tomultiple different ethylene conversion reactor systems and processes110, e.g., ethylene conversion systems 110 a-110 e, which each producedifferent hydrocarbon products, e.g., products 120 a-120 e.

As noted, the fluid connection between the OCM reactor system 100 andeach of the different ethylene conversion systems 110 a-110 e, can be acontrollable and selective connection in some embodiments, e.g., a valveand control system, that can apportion the output of the OCM reactorsystem to one, two, three, four, five or more different ethyleneconversion systems. Valve and piping systems for accomplishing this maytake a variety of different forms, including valves at each pipingjunction, multiport valves, multi-valve manifold assemblies, and thelike.

Ethylene-to-Liquids (ETL) Systems

Ethylene-to-liquids (ETL) systems and methods of the present disclosurecan be used to form various products, including hydrocarbon products.Products and product distributions can be tailored to a givenapplication, such as products for use as fuel (e.g., jet fuel orautomobile fuels such as diesel or gasoline).

The present disclosure provides reactors for the conversion of olefinsto higher molecular weight hydrocarbons, which can be in liquid form.Such reactors can be ETL reactors, which can be used to convert ethyleneand/or other olefins to higher molecular weight hydrocarbons.

An ETL system (or sub-system) can include one or more reactors. An ETLsystem can include at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,14, 15, 16, 17, 18, 19, or 20 ETL reactors, which can be in a parallel,serial, or a combination of parallel and serial configuration.

An ETL reactor can be in the form of a tube, packed bed, moving bed orfluidized bed.

An ETL reactor can include a single tube or multiple tubes, such as atube in a shell. A multi-tubular reactor can be used for highlyexothermic conversions, such as the conversion of ethylene to otherhydrocarbons. Such a design can allow for an efficient management ofthermal fluxes and the control of reactor and catalyst bed temperatures.

An ETL reactor can be an isothermal or adiabatic reactor. An ETL reactorcan have one or more of the following: 1) multiple cooling zones andarrangements within the reactor shell in which the temperature withineach cooling zone may be independently set and controlled; 2) multipleresidence times of the reactants as they traverse the tubular reactorfrom the inlet of the individual tubes to the outlet; and 3) multiplepass design in which the reactants may make several passes within thereactor shell from the inlet of the reactor to the outlet.

Multi-tubular reactors of the present disclosure can be used to convertethylene to liquid hydrocarbons in a variety of ways. In some cases, thedisclosed multi-tubular ETL reactors can result in smaller reactors andgas compressors compared to adiabatic ETL designs. The ETL hydrocarbonreaction is exothermic and thus reaction heat management may beimportant for reaction control and improved product selectivity. Inadiabatic ETL reactor designs, there is an upper limit to the ethyleneconcentration that is flowed through reactor due to the amount of heatreleased and subsequent temperature rise inside the reactor. To controlthe heat of reaction, adiabatic reactors can use a large amount ofdiluent gas to mitigate the temperature rise in the reactor bed. In somecases, the heat of reaction can be managed using multiple reactors withcooling between reactors and limited conversion between reactors (i.e.,about 20%, about 30%, about 40%, about 50%, about 60%, or about 70%conversion in one reactor), cooling of the product effluent, andconverting the remaining feedstock in one or more subsequent reactors.The use of diluent gas can result in larger catalyst beds, reactors, andgas compressors. The multi-tubular reactors described herein can allowfor significantly greater ethylene concentrations while controlling thereactor bed temperature, since heat can be removed at the reactor wall.As a consequence, for a targeted rate of production, smaller catalystbeds, reactors, and gas compressors may be used.

In addition to smaller ETL reactors, the disclosed multi-tubular ETLreactors can result in smaller downstream liquid-gas product separationequipment due to less diluent gas needed to cool the reactor.

Multi-tubular ETL reactors of the present disclosure can result in morefavorable process conditions toward higher carbon number hydrocarbonliquids compared to an adiabatic ETL design. Relative to adiabaticreactors where ethylene feed can be diluted to control reactiontemperature, the disclosed multi-tubular designs can allow for moreconcentrated ethylene feed into the reactor while maintaining goodreactor temperature control. Higher ethylene concentration in thereactor can facilitate the formation for higher hydrocarbon liquids suchas jet and/or diesel fuel since reactant concentration is importantprocess parameter to yield higher hydrocarbon oligomers. In some cases,olefinic liquids of specific carbon number range and types can also berecycled into the reactor bed to further generate higher carbon numberliquids (e.g., jet/diesel).

Multi-tubular reactors can have multiple temperature zones and offermultiple residence times. This can allow a wide range of processflexibility to target a particular product slate. As an example, areactor can have multiple temperature zones and/or residence times. Oneuse of this design can be to make jet and/or diesel fuel from ethylene.Ethylene oligomerization can require a relatively high reactiontemperature. The temperature required to react ethylene, to start theoligomerization process may not be compatible with jet or dieselproducts, due to the rapid cracking and/or disproportionation of thesejet/diesel products at elevated temperatures. Multiple reactortemperature zones can allow for a separate and higher temperature zoneto start ethylene oligomerization while having another lower temperaturezone to facilitate further oligomerization into jet/diesel fuel whilediscouraging cracking and disproportionation side reactions.

The use of multiple temperature zones may require different residencetimes within a reactor bed. In the jet/diesel example, the residencetime for the ethylene reaction can be different than the residence timefor a lower temperature finishing step to form jet/diesel. To maximizejet/diesel liquid yield, the ethylene oligomerization reaction bedtemperature may need to be higher but with a lower residence time thanthe step to make jet/diesel which can require a lower temperature buthigher residence time. In adiabatic ETL reactors, multi-temperatureprocesses may occur over multiple reactor beds with a differenttemperature associated with each reactor. The multi-temperature zoneapproach disclosed herein can obviate the need for multiple reactors, asin the adiabatic ETL case, since multiple temperature zones can beachieved within a single reactor and thus lower capital outlay forreactor deployment.

Catalyst aging can be an important design constraint in ETL reactionengineering. ETL catalysts can deactivate over time until the catalystbed is no longer able to sustain high ethylene conversion. A slowercatalyst deactivation rate may be desired since more ethylene can beconverted per catalyst bed before the catalyst bed can need to be takenoff-line and regenerated. Typically, the catalyst deactivates due to“coke”, deposits of carbonaceous material, which results in decreasingcatalyst performance upon coke build-up. The rate of “coke” build-up isattributable to many different parameters. In ETL adiabatic reactors,the formation of catalyst bed “hot-spots” can play an important role incausing catalyst coking. “Hot-spots” favor aromatic compound formation,which are precursors to coke formation. “Hot-spots” are a result oftemperature non-uniformities within the catalyst bed due to inadequateheat transfer. The localized “hot-spots” increase the rate of catalystcoking/deactivation. The disclosed multi-tubular design can decreaselocalized “hot-spots” due to better heat transfer properties of themulti-tubular design relative to the adiabatic design. It is anticipatedthat the decrease in catalyst “hot-spots” can slow catalystdeactivation.

The product slate of the ETL slate is a result of many factors. Animportant factor is the catalyst bed temperature. For example, highertemperatures catalyst bed temperatures can skew the product slate, forsome catalysts, to aromatic products. In large adiabatic reactors,controlling “hot spot” formation is challenging and inhomogeneities inthe catalyst bed temperature profiles lead a wider distribution ofproducts. The proposed multi-tubular design can significantly reducecatalyst bed temperature inhomogeneities/“hot spots” due to better heattransfer characteristics relative to the adiabatic design. As a result,a narrower product distribution can be more readily achieved than withadiabatic reactor design. While the multi-tubular design providesexcellent catalyst bed temperature uniformity, catalyst bed temperaturebed uniformity can be further enhanced by injection of “trim gas” and/or“trim liquid.”

The heat capacity of“trim gas” can be used to fine-tune the catalyst bedto a target temperature. Trim gas composition can be inert/high heatcapacity gas for example: ethane, propane, butane, and other high heatcapacity hydrocarbons.

In some cases, liquid hydrocarbons can be injected into the ETL reactorsto take advantage of the heat of vaporization to further regulate andcool the reactor bed in order to achieve the desired temperature. Also,one can use both of them (gases and liquids) as “trim” agents in thisdesign for ETL.

ETL catalysts may need to be regenerated from a state of low ethyleneconversion (e.g., 20% or less) to high ethylene conversion, such as,e.g., greater than 20%, 30%, 40%, 50%, 60%, or 70%. Regeneration canoccur by heating the catalyst bed to an appropriate temperature whileintroducing a portion of diluted air. The oxygen in air can be used toremove coke by combustion and thus renew catalyst activity. Too muchoxygen can cause uncontrolled combustion, a highly exothermic process,and the resultant catalyst bed temperature rise may cause irreversiblecatalyst damage. As a consequence, the amount of air that is permittedduring adiabatic reactor regeneration is limited and monitored.

The catalyst regeneration time for an adiabatic reactor can be largelydictated by the amount of oxygen that can be permitted in the reactor.The greater heat transfer properties of the disclosed multi-tubularreactors can permit greater concentrations of oxygen during catalystregeneration to hasten catalyst regeneration while ensuring that thecatalyst bed temperature does not reach the point of irreversiblecatalyst deactivation.

The present disclosure also provides reactor systems for carrying outethylene conversion processes. A number of ethylene conversion processescan involve exothermic catalytic reactions where substantial heat isgenerated by the process. Likewise, for a number of these catalyticsystems, the regeneration processes for the catalyst materials likewiseinvolve exothermic reactions. As such, reactor systems for use in theseprocesses can generally be configured to effectively manage excessthermal energy produced by the reactions, in order to control thereactor bed temperatures to most efficiently control the reaction,prevent deleterious reactions, and prevent catalyst or reactor damage ordestruction.

Tubular reactor configurations that may present high wall surface areaper unit volume of catalyst bed may be used for reactions where thermalcontrol is desirable or otherwise required, as they can permit greaterthermal transfer out of the reactor. Reactor systems that includemultiple parallel tubular reactors may be used in carrying out theethylene conversion processes described herein. In particular, arrays ofparallel tubular reactors each containing the appropriate catalyst forone or more ethylene conversion reaction processes may be arrayed withspace between them to allow for the presence of a cooling medium betweenthem. Such cooling medium may include any cooling medium appropriate forthe given process. For example, the cooling medium may be air, water orother aqueous coolant formulations, steam, oil, upstream of reactionfeed or for very high temperature reactor systems, molten salt coolants.

In some cases, reactor systems are provided that include multipletubular reactors segmented into one, two, three, four or more differentdiscrete cooling zones, where each zone is segregated to contain itsown, separately controlled cooling medium. The temperature of eachdifferent cooling zone may be independently regulated through itsrespective cooling medium and an associated temperature control system,e.g., thermally connected heat exchangers, etc. Such differentialcontrol of temperature in different reactors can be used todifferentially control different catalytic reactions, or reactions thathave catalysts of different age. Likewise, it allows for the real timecontrol of reaction progress in each reactor, in order to maintain amore uniform temperature profile across all reactors, and thereforesynchronize catalyst lifetimes, regeneration cycles and replacementcycles.

Differentially cooled tubular reactor systems are schematicallyillustrated in FIG. 2. As shown, an overall reactor system 200 includesmultiple discrete tubular reactors 202, 204, 206 and 208 containedwithin a larger reactor housing 210. Within each tubular reactor isdisposed a catalyst bed for carrying out a given catalytic reaction. Thecatalyst bed in each tubular reactor may be the same or it may bedifferent from the catalyst in the other tubular reactors, e.g.,optimized for catalyzing a different reaction, or for catalyzing thesame reaction under different conditions. As shown, the multiple tubularreactors 202, 206, 208 and 210 share a common manifold 212 for thedelivery of reactants to the reactors. However, each individual tubularreactor or subset of the tubular reactors may alternatively include asingle reactant delivery conduit or manifold for delivering reactants tothat tubular reactor or subset of reactors, while a separate deliveryconduit or manifold is provided for delivery of the same or differentreactants to the other tubular reactors or subsets of tubular reactors.

As an alternative or in addition to, the reactor systems used inconjunction with the olefin (e.g., ethylene) conversion processesdescribed herein can provide for variability in residence time forreactants within the catalytic portion of the reactor. Residence timewithin a reactor can be varied through the variation of any of a numberof different applied parameters, e.g., increasing or decreasing flowrates, pressures, catalyst bed lengths, etc. However, a single reactorsystem may be provided with variable residence times, despite sharing asingle reactor inlet, by varying the volume of different reactor tubesor reactor tube portions within a single reactor unit (“catalyst bedlength”). As a result of varied volumes among reactor tubes or reactortube portions into which reactants are being introduced at a given flowrate, residence times for those reactants within those varied volumereactor tubes or reactor tube portions, can be consequently varied.

Variation of reactor volumes may be accomplished through a number ofapproaches. By way of example, varied volume may be provided byincluding two or more different reactor tubes into which reactants areintroduced at a given flow rate, where the two or more reactor tubeseach have different volumes, e.g., by providing varied diameters. As canbe appreciated, the residence time of gases being introduced at the sameflow rate into two or more different reactors having different volumescan be different. In particular, the residence time can be greater inthe higher volume reactors and shorter in the smaller volume reactors.The higher volume within two different reactors may be provided byproviding each reactor with different diameters. Likewise, one can varythe length of the reactors catalyst bed, in order to vary the volume ofthe catalytic portion.

Alternatively, or additionally, the volume of an individual reactor tubecan be varied by varying the diameter of the reactor along its length,effectively altering the volume of different segments of the reactor.Again, in the wider reactor segments, the residence time of gas beingintroduced into the reactor tube can be longer in the wider reactorsegments than in the narrower reactor segments.

Varied volumes can also be provided by routing different inlet reactantstreams to different numbers of similarly sized reactor conduits ortubes. In particular, reactants, e.g., gases, may be introduced into asingle reactor tube at a given flow rate to yield a particular residencetime within the reactor. In contrast, reactants introduced at the sameflow rate into two or more parallel reactor tubes can have a much longerresidence time within those reactors.

The above-described approaches to varying residence time within reactorcatalyst beds are illustrated with reference to FIGS. 3-4. FIG. 3schematically illustrates a reactor system 300 in which two or moretubular reactors 302 and 304 are disposed, each having its own catalystbed, 306 and 308, respectively, disposed therein. The two reactors areconnected to the same inlet manifold such that the flow rate ofreactants being introduced into each of reactors 302 and 304 are thesame. Because reactor 304 has a larger volume (shown as a widerdiameter), the reactants can be retained within catalyst bed 308 for alonger period. In particular, as shown, reactor 304 has a largerdiameter, resulting in a slower linear velocity of reactants through thecatalyst bed 308, than the reactants passing through catalyst bed 306.As noted above, one can similarly increase residence time within thecatalyst bed of reactor 304 by providing a longer reactor. However, suchlonger reactor bed may be required to have similar back pressure as ashorter reactor to ensure reactants are introduced at the same flow rateas the shorter reactor

FIG. 4 schematically illustrates an alternative approach for varyingreactor volumes in order to vary residence times of reactants in thecatalyst bed. As shown, an individual reactor unit, e.g., reactor tube400, can be configured to provide for differing residence times withindifferent portions of the reactor tube by varying the diameter of thereactor between reactor segment 404, 406 and 408. In particular, byproviding a larger diameter of the reactor tube in segment 404 and 406,respectively, one can increase the residence time of reactants movingthrough these segments, as the linear velocity of the reactants throughsuch segments decreases.

The residence time of reactants within reactor systems can be controlledby varying the diameter of the ETL reactor along the path of fluid flow.In some cases, the reactor system can include multiple different reactortubes, where each reactor tube includes a catalyst bed disposed therein.Differing residence times may be employed in catalyzing differentcatalytic reactions, or catalyzing the same reactions under differingconditions. In particular, one may wish to vary residence time of agiven set of reactants over a single catalyst system, in order tocatalyze a reaction more completely, catalyze a different or furtherreaction, or the like. Likewise, different reactors within the systemmay be provided with different catalyst systems that may benefit fromdiffering residence times of the reactants within the catalyst bed tocatalyze the same or different reactions from each other.

Alternatively or additionally, residence times of reactants withincatalyst beds may be configured to optimize thermal control within theoverall reactor system. In particular, residence times may be longer ata zone in the reactor system in which removal of excess thermal energyis less critical or more easily managed, e.g., because the overallreaction has not yet begun generating excessive heat. In contrast, inother zones of the reactor, e.g., where removal of excess thermal energyis more difficult due to rapid exothermic reactivity, the reactorportion may only maintain the reactants for a much shorter time, byproviding a narrower reactor diameter. As can be appreciated, thermalmanagement becomes easier due to the shorter period of time that thereactants are present and reacting to produce heat. Likewise, thereduced volume of a tubular reactor within a reactor housing alsoprovides for a greater volume of cooling media, to more efficientlyremove thermal energy.

Systems and methods of the present disclosure can employ fixed bedreactors. Fixed bed reactors can be adiabatic reactors. Fixed bedadiabatic ETL reactors can provide for simplicity of the reactor design.No active external cooling mechanism of the reactor may be necessary. Tocontrol the reactor temperature, profile dilution of the reactive olefinor other feedstocks (e.g., ethylene, propylene, butenes, pentenes, etc.)may be necessary. The diluent gas can be any material that isnon-reactive or non-poisonous to the ETL catalyst but preferably has ahigh heat capacity to moderate the temperature rise within the catalystbed. Examples of diluent gases include nitrogen (N₂), argon, methane,ethane, propane and helium. The reactive part of the feedstock can bediluted directly or diluted indirectly in the reactor by recyclingprocess gas to dilute the feedstock to an acceptable concentration.Temperature profile can also be controlled by internal reactor heatexchangers that can actively control the heat within the catalyst bed.Catalyst bed temperature control can also be achieved by limitingfeedstock conversion within the catalyst bed. To achieve full feedstockconversion in this scenario, fixed bed adiabatic reactors are placed inseries with heat exchangers between reactors to moderate temperaturerise reactor over reactor. Partial conversion occurs in each reactorwith inter-stage cooling to achieve the desired conversion andselectivity for the ETL process.

Since ETL catalysts can deactivate over time through coke deposition,the fixed bed reactors can be taken off-line and regenerated, such as byan oxidative or non-oxidative process, as described elsewhere herein.Once regenerated to full activity the ETL reactors can be put backon-line to process more feedstock.

Systems and methods of the present disclosure can employ the use of ETLcontinuous catalyst regeneration reactors. Continuous catalystregeneration reactors (CCRR) can be attractive for processes where thecatalyst deactivates over time and need to be taken off-line to beregenerated. By regenerating the catalyst in a continuous fashion lesscatalyst, fewer reactors for the process as well as fewer requiredoperations are to regenerate the catalyst. There are two classes ofdeployments for CCRR reactors: (1) moving bed reactors and (2) fluidizedbed reactors. In moving bed CCRR design, the pelletized catalyst bedmoves along the reactor length and is removed and regenerated in aseparate vessel. Once the catalyst is regenerated the catalyst pelletsare put back in the ETL conversion reactor to process more feedstock.The online/regeneration process can be continuous and can maintain aconstant flow of active catalyst in the ETL reactor. In fluidized bedETL reactors, ETL catalyst particles are “fluidized” by a combination ofETL process gas velocity and catalyst particle weight. During bedfluidization, the bed expands, swirls, and agitates during reactoroperation. The advantages of an ETL fluidized bed reactor are excellentmixing of process gas within the reactor, uniform temperature within thereactor, and the ability to continuously regenerate the coked ETLcatalyst.

Other reactor designs, such as moving bed (MBR), fluidized bed, andslurry bed reactors can also be employed. An exemplary fluidized bedreactor 410 is shown in FIG. 4B. A gas inlet stream 411 enters at thebottom of the reactor and a gas outlet stream 412 exits from the top ofthe reactor. Solid particles (e.g., catalyst) enter 413 at one side andexit 414 at another. Within the fluidized bed, gas bubbles 415 canencounter solid particles 416. The reactor can comprise a distributor417 for distributing the gas flow. FIG. 4C shows additional schematicsof exemplary reactor configurations for co-current moving bed reactors(420), counter-current moving bed reactors (430), fluidized bed reactors(440), and slurry bed reactors (450). The moving bed and fluidized bedreactors have separate gas inlet (421, 431, 434), gas outlet (422, 432,442), catalyst inlet (423, 433, 443), and catalyst outlet (424, 434,444) configurations. The slurry bed reactor has a combined gas/catalystinlet 451 and gas/catalyst outlet 452.

The ETL catalyst can be regenerated with methane or natural gas. Theregeneration stream can have oxygen (O₂) or other oxidizing agent. Theconcentration of oxygen in the regeneration stream can be below thelimiting oxygen concentration (LOC), such that the mixture is notflammable. In some embodiments, the concentration of O₂ in theregeneration stream is less than about 6%, less than about 5%, less thanabout 4%, less than about 3%, less than about 2%, or less than about 1%.In some cases, the concentration of O₂ in the regeneration stream isbetween 0% and about 3%. An advantage of regenerating the ETL catalystwith methane or natural gas is that, following flowing over the ETLcatalyst for regeneration, the stream can be used in the OCM and/or ETLprocess (e.g., the stream can be combusted to provide energy). The useof methane and/or natural gas to regenerate the ETL catalyst may notintroduce any new components into the process to achieve catalystregeneration, which can lead to an efficient use of materials. In somecases, the use of methane and/or natural gas makes the economics of theprocess insensitive, or less dependent on, the period of time that theETL catalyst can operate between regeneration cycles.

Catalysts for the Conversion of Olefins to Liquids

The present invention also provides catalysts and catalyst compositionsfor ethylene conversion processes, in accordance with the processesdescribed herein. In some embodiments, the disclosure provides modifiedzeolite catalysts and catalyst compositions for carrying out a number ofdesired ethylene conversion reaction processes. In some cases, providedare impregnated or ion exchanged zeolite catalysts useful in conversionof ethylene to higher hydrocarbons, such as gasoline or gasolineblendstocks, diesel and/or jet fuels, as well as a variety of differentaromatic compounds. For example, where one is using ethylene conversionprocesses to convert OCM product gases to gasoline or gasoline feedstockproducts or aromatic mixtures, one may employ modified ZSM catalysts,such as ZSM-5 catalysts modified with Ga, Zn, Al, or mixtures thereof.In some cases, Ga, Zn and/or Al modified ZSM-5 catalysts are preferredfor use in converting ethylene to gasoline or gasoline feedstocks.Modified catalyst base materials other than ZSM-5 may also be employedin conjunction with the invention, including, e.g., Y, ferrierite,mordenite, and additional catalyst base materials described herein.

In some cases, ZSM catalysts, such as ZSM-5 are modified with Co, Fe,Ce, or mixtures of these and are used in ethylene conversion processesusing dilute ethylene streams that include both carbon monoxide andhydrogen components (See, e.g., Choudhary, et al., Microporous andMesoporous Materials 2001, 253-267, which is incorporated herein byreference). In particular, these catalysts can be capable ofco-oligomerizing the ethylene and H₂ and CO components into higherhydrocarbons, and mixtures useful as gasoline, diesel or jet fuel orblendstocks of these. In such embodiments, a mixed stream that includesdilute or non-dilute ethylene concentrations along with CO/H₂ gases canbe passed over the catalyst under conditions that cause theco-oligomerization of both sets of feed components. Use of ZSM catalystsfor conversion of syngas to higher hydrocarbons can be described in, forexample, Li, et al., Energy and Fuels 2008, 22:1897-1901, which isincorporated herein by reference in its entirety.

The present disclosure provides various catalysts for use in convertingolefins to liquids. Such catalysts can include an active material on asolid support. The active material can be configured to catalyze an ETLprocess to convert olefins to higher molecular weight hydrocarbons.

ETL reactors of the present disclosure can include various types of ETLcatalysts. In some cases, such catalysts are zeolite and/or amorphouscatalysts. Examples of zeolite catalysts include ZSM-5, Zeolite Y, Betazeolite and Mordenite. Examples of amorphous catalysts include solidphosphoric acid and amorphous aluminum silicate. Such catalysts can bedoped, such as using metallic and/or semiconductor dopants. Examples ofdopants include, without limitation, Ni, Pd, Pt, Zn, B, Al, Ga, In, Be,Mg, Ca and Sr. Such dopants can be situated at the surfaces, in the porestructure of the catalyst and/or bulk regions of such catalysts.

Catalyst can be doped with materials that are selected to effect a givenor predetermined product distribution. For example, a catalyst dopedwith Mg or Ca can provide selectivity towards olefins for use ingasoline. As another example, a catalyst doped with Zn or Ga (e.g.,Zn-doped ZSM-5 or Ga-doped ZSM-5) can provide selectivity towardsaromatics. As another example, a catalyst doped with Ni (e.g., Ni-dopedzeolite Y) can provide selectivity towards diesel or jet fuel.

Catalysts can be situated on solid supports. Solid supports can beformed of insulating materials, such as TiOx or AlOx, wherein ‘x’ is anumber greater than zero, or ceramic materials.

Catalyst of the present disclosure can have various cycle lifetimes(e.g., the average period of time between catalyst regeneration cycles).In some cases, ETL catalysts can have lifetimes of at least about 50hours, 100 hours, 110 hours, 120 hours, 130 hours, 140 hours, 150 hours,160 hours, 170 hours, 180 hours, 190 hours, 200 hours, 210 hours, 220hours, 230 hours, 240 hours, 250 hours, 300 hours, 350 hours, or 400hours. At such cycle lifetimes, olefin conversion efficiencies less thanabout 90%, 85%, 80%, 75%, 70%, 65%, or 60% may be observed.

Catalysts of the present disclosure can be regenerated through variousregeneration procedures, as described elsewhere herein. Such procedurescan increase the total lifetimes of catalysts (e.g., length of timebefore the catalyst is disposed of). An example of a catalystregeneration process is provided in Lubo Zhou, “BP-UOP Cyclar Process,”Handbook of Petroleum Refining Processes, The McGraw-Hill Companies(2004), pages 2.29-2.38, which is entirely incorporated herein byreference.

In some embodiments, ETL catalysts can be comprised of base materials(first active components) and dopants (second active components). Thedopants can be introduced to the base materials through appropriatemethods and procedures, such as vapor or liquid phase deposition.Dopants can be selected from a variety of elements, including metallic,non-metallic or amphoteric in forms of elementary substance, ions orcompounds. A few representative doping elements are Ga, Zn, Al, In, Ni,Mg, B and Ag. Such dopants can be provided by dopant sources. Forexample, silver can be provided by way of AgCl or sputtering. Theselection of doping materials can depend on the target product nature,such as product distribution. For example, Ga is favorable foraromatics-rich liquid production while Mg is favorable foraromatics-poor liquid production.

Base materials can be selected from crystalline zeolite materials, suchas ZSM-5, ZSM-11, ZSM-22, Y, beta, mordenite, L, ferrierite, MCM-41,SAPO-34, SAPO-11, TS-1, SBA 15 or amorphous porous materials, such asamorphous silicoaluminate (ASA) and solid phosphoric acid catalysts. Thecations of these materials can be NH₄ ⁺, H⁺ or others. The surface areasof these materials can be in a range of 1 m²/g to 10000 m²/g, 10 m²/g to5000 m²/g, or 100 m²/g to 1000 m²/g. The base materials can be directlyused for synthesis or undergo some chemical treatment, such asdesilication (de-Si) or dealumination (de-Al) to further modify thefunctionalities of these materials.

The base materials can be directly used for synthesis or undergochemical treatment, such as desilication (de-Si) or dealumination(de-Al), to get derivatives of the base materials. Such treatment canimprove the catalyst lifetime performance by creating larger porevolumes, such as pores having diameters greater than or equal to about 1nanometer (nm), 2 nm, 3 nm, 4, nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50nm, or 100 nm. In some cases, mesopores having diameters between about 1nm and 100 nm, or 2 nm and 50 nm are created. In some examples, silicaor alumina, or a combination of silica and alumina, can be etched fromthe base material to make a larger pore structure in the base catalystthat can enhance diffusion of reactants and products into the catalystmaterial. Pore diameter(s) and volume, in addition to porosity, can beas determined by adsorption or desorption isotherms (e.g.,Brunauer-Emmett-Teller (BET) isotherm), such as using the method ofBarrett-Joyner-Halenda (BJH). See Barrett E. P. et al., “Thedetermination of pore volume and area distributions in poroussubstances. I. Computations from nitrogen isotherms,” J. Am. Chem. Soc.1951. V. 73. P. 373-380. Such method can be used to calculate materialporosity and mesopore volumes, in some cases volumes that are 3-7 timeslarger than their original materials. In general, any changes incatalyst structure, composition and morphology can be measured bytechnologies of BET, SEM and TEM, etc.

There are various approaches for doping catalysts. In an example, thedoping components can be added to the base materials and theirderivatives through impregnation, in some cases using incipient wetnessimpregnation (IWI), ion exchange or framework substitution in a zeolitesynthesis operation. In some cases, IWI can include i) mixing a saltsolution of the doping component with base material, for which theamount of salt is calculated based on doping level, ii) drying themixture in an oven, and iii) calcining the product at a certaintemperature for a certain time, typically 550-650° C., 6-10 hrs. Ionexchange catalyst synthesis can include i) mixing a salt solution, whichcan contain at least 1.5, 2, 3, 4, 5, 6, 7, 8, 9, or 10 times excessamount of the doping component, with base material, ii) heating themixture, such as, for example, at a temperature from about 50° C. to100° C., 60° C. to 90° C., or 70° C. to 80° C. for a time period of atleast about 10 minutes, 30 minutes, 1 hour, 2 hours, 3 hours, 4 hours, 5hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, or 12hours, to conduct a first ion exchange, iii) separating the first ionexchange mother solution, iv) adding a new salt solution and repeatingii) and iii) to conduct a second ion exchange, v) washing the wet solidwith deionized water to remove or lower the concentration of solublecomponents, vi) drying the raw product, such as air drying or in anoven, and vii) calcining the raw product at a temperature from about450° C. to 800° C., 500° C. to 750° C., or 550° C. to 650° C. for a timeperiod from about 1 hour to 24 hours, 4 hours to 12 hours, or 6 hours to10 hours.

In some situations, powder catalysts prepared according to methods ofthe present disclosure may need to be formed prior to prepared inpredetermined forms (or form factors) prior to use. In some examples,the forms can be selected from cylinder extrudates, rings, trilobe, andpellets. The sizes of the forms can be determined by reactor size. Forexample, for a 1″-2″ internal diameter (ID) reactor, 1.7 mm to 3.0 mmextrudates or equivalent size for other forms can be used. Larger formscan be used for different commercial scales (such as 5 mm forms). TheETL reactor inner diameter (ID) can be any diameter, including rangingfrom 2 inches to 10 feet, from 1 foot to 6 feet, and from 3 feet to 4feet. In commercial reactors, the diameters of the catalyst (e.g.,extrudate) can be greater than about 3 mm, greater than about 4 mm,greater than about 5 mm, greater than about 7 mm, greater than about 10mm, greater than about 15 mm, or greater than about 20 mm. Bindingmaterials (binder) can be used for forming the catalysts and improvingcatalyst particle strength. Various solid materials that are inerttowards olefins (e.g., ethylene), such as Boehmite, alumina, silicate,Bentonite, or kaolin, can be used as binders.

A wide range of catalyst:binder ratio can be used, such as, from about95:5 to 30:70, or 90:10 to 50:50. In some cases, a ratio of 80:20 isused for bench scale and pilot reactor catalyst synthesis. For formedcatalysts, the crush strengths can be in the range of about 1 N/mm to 60N/mm, 5 N/mm to 30 N/mm, or 7 N/mm to 15 N/mm.

Catalysts prepared according to methods of the present disclosure can betested for the production of various hydrocarbon products, such asgasoline and/or aromatics production. In some cases, such catalysts aretested for the production of both gasoline and aromatics.

In an example, a short-term test condition for gasoline production is300° C., atmospheric pressure, WHSV=0.65 hr⁻¹, N₂ 50% and C₂H₄ 50%, twohour runs. In another example, a short-term test condition for aromaticsproduction is 450° C., atmospheric pressure, WHSV=1.31 hr⁻¹, N₂ 50% andC₂H₄ 50%, two hour runs. In addition to conducting the two hourshort-term test to obtain the initial catalytic activity data, for someselected catalysts, the long-term test (lifetime test) are alsoperformed to obtain data of catalyst lifetime, catalyst capacity as wellas average product composition over the lifetime runs.

In an example, the results on an initial catalytic activity test atgasoline production conditions is C₂H₄ conversion greater than about99%, C₅₊ C mole selectivity greater than about 65% (e.g., 65%-70%), andC₅₊ C mole yield greater than about 65% (e.g., 65%-70%). Catalystlifetime performance in one cycle run at gasoline conditions can be atleast about 189 hours, cut at conversion down to 80%; catalyst capacityis about 182 g-C₂H₄ converted per g-catalyst with C mole yield ofC₅₊+C³⁻C⁴⁻ greater than about 70%. With recycling, C³⁻ and C⁴⁻ can beaccounted as liquid products.

In another example, the results on an initial catalytic activity ataromatics production conditions is C₂H₄ conversion greater than about99%, C₅ ⁺C mole selectivity greater than about 75% (e.g., 75-80%), C₅₊ Cmole yield greater than about 75% (e.g., 75-80%) and aromatics in C₅₊greater than about 90%. Catalyst lifetime performance in one cycle runat aromatics production conditions can be at least about 228 hours, cutat conversion down to 82%, catalyst capacity 143 g-C₂H₄converted/g-catalyst with average C₅₊ yield around 72% and aromaticsyield around 62%.

An ETL catalysts can have a porosity that is selected to optimizecatalyst performance, including selectivity, lifetime, and productoutput. The porosity of an ETL catalyst can be between about 4 Angstromsto about 1 micrometer, from 0.01 nm to 500 nm, from 0.1 nm to 100 nm, orfrom 1 nm to 10 nm as measured by pore symmetry (e.g., nitrogenporosimetry). An ETL catalyst can have a base material with a set ofpores that have an average pore size (e.g., diameter) from about 4Angstroms to 100 nm, or 4 Angstroms to 10 nm, or 4 Angstroms to 10Angstroms.

The catalytic materials may also be employed in any number of forms. Inthis regard, the physical form of the catalytic materials may contributeto their performance in various catalytic reactions. In particular, theperformance of a number of operating parameters for a catalytic reactorthat impact its performance can be significantly impacted by the form inwhich the catalyst is disposed within the reactor. The catalyst may beprovided in the form of discrete particles, e.g., pellets, extrudates orother formed aggregate particles, or it may be provided in one or moremonolithic forms, e.g., blocks, honeycombs, foils, lattices, etc. Theseoperating parameters include, for example, thermal transfer, flow rateand pressure drop through a reactor bed, catalyst accessibility,catalyst lifetime, aggregate strength, performance, and manageability.

In some cases, it is also desirable that the catalyst forms used willhave crush strengths that meet the operating parameters of the reactorsystems. In particular, a catalyst particle crush strength shouldgenerally support both the pressure applied to that particle from theoperating conditions, e.g., gas inlet pressure, as well as the weight ofthe catalyst bed. In general, it is desirable that a catalyst particlehave a crush strength that is greater than about 1 N/mm², and preferablygreater than about 10 N/mm², for example greater than 1 N/mm², andpreferably greater than 10 N/mm². As will be appreciated, crush strengthmay be increased through the use of catalyst forms that are morecompact, e.g., having lower surface to volume ratios. However, adoptingsuch forms may adversely impact performance. Accordingly, forms arechosen that provide the above described crush strengths within thedesired activity ranges, pressure drops, etc. Crush strength is alsoimpacted though use of binder and preparation methods (e.g., extrusionor pelleting).

For example, in some embodiments the catalytic materials are in the formof an extrudate or pellet. Extrudates may be prepared by passing asemi-solid composition comprising the catalytic materials through anappropriate orifice or using molding or other appropriate techniques.Pellets may be prepared by pressing a solid composition comprising thecatalytic materials under pressure in the die of a tablet press. Othercatalytic forms include catalysts supported or impregnated on a supportmaterial or structure. In general, any support material or structure maybe used to support the active catalyst. The support material orstructure may be inert or have catalytic activity in the reaction ofinterest. For example, catalysts may be supported or impregnated on amonolith support. In some particular embodiments, the active catalyst isactually supported on the walls of the reactor itself, which may serveto minimize oxygen concentration at the inner wall or to promote heatexchange by generating heat of reaction at the reactor wall exclusively(e.g., an annular reactor in this case and higher space velocities).

The stability of the catalytic materials is defined as the length oftime a catalytic material will maintain its catalytic performancewithout a significant decrease in performance (e.g., adecrease >20%, >15%, >10%, >5%, or greater than 1% in hydrocarbon orsoot combustion activity). In some embodiments, the catalytic materialshave stability under conditions required for the hydrocarbon combustionreaction of >1 hr, >5 hrs, >10 hrs, >20 hrs, >50 hrs, >80 hrs, >90hrs, >100 hrs, >150 hrs, >200 hrs, >250 hrs, >300 hrs, >350 hrs, >400hrs, >450 hrs, >500 hrs, >550 hrs, >600 hrs, >650 hrs, >700 hrs, >750hrs, >800 hrs, >850 hrs, >900 hrs, >950 hrs, >1,000 hrs, >2,000hrs, >3,000 hrs, >4,000 hrs, >5,000 hrs, >6,000 hrs, >7,000 hrs, >8,000hrs, >9,000 hrs, >10,000 hrs, >11,000 hrs, >12,000 hrs, >13,000hrs, >14,000 hrs, >15,000 hrs, >16,000 hrs, >17,000 hrs, >18,000hrs, >19,000 hrs, >20,000 hrs, >1 yrs, >2 yrs, >3 yrs, >4 yrs or >5 yrs.

Catalyst Poisoning

Catalysts of the present disclosure can be poisoned during the course ofcatalytically generating a given product. ETL catalysts, for instance,can be poisoned upon generating higher molecular weight hydrocarbonsfrom olefins (e.g., ethylene). The present disclosure provides variousapproaches for avoiding such poisons.

Alkynes can be oligomerized over ETL catalysts, such as zeolites or acidcatalysts. During alkyne oligomerization, the alkynes can be rapidlytransformed into polyaromatic molecules, precursors to coke, which candeactivate the catalyst. The selectivity for acetylene to make coke candeactivate the ETL catalyst at a faster rate than an alkene and thecatalyst may need to be taken off line to be regenerated. Any moleculecontaining an alkyne functional group can deactivate the ETL catalyst ata faster rate than an alkene group. One example is acetylene, an alkyneproduced in small quantities within the OCM process.

An approach for eliminating alkynes from feedstock to an ETL catalyst isto convert the alkynes to other material that may not poison the ETLcatalyst. For example, alkynes can be selectively hydrogenated to makeolefins using a variety of transition metal catalysts withouthydrogenating the olefins into alkanes. Examples of these catalysts arePd, Fe, Co, Ni, Zn, and Cu containing catalysts. Such catalysts can beincorporated in or more reactors upstream of ETL catalysts.

Dienes can be oligomerized over ETL catalysts, such as zeolites or acidcatalysts.

However during diene oligomerization, dienes can be rapidly transformedinto polydienes molecules, precursors to coke, which can deactivate theETL catalyst. The selectivity for dienes to make coke can rapidlydeactivate the ETL catalyst and the catalyst may need to be taken offline to be regenerated. Any molecule containing a diene functional groupcan rapidly deactivate the ETL catalyst. An example is butadiene, adiene produced in small quantities within the OCM process.

An approach for eliminating dienes from feedstock to an ETL catalyst isto convert the dienes to other material that may not poison the ETLcatalyst. For example, dienes can be selectively hydrogenated to makeolefins using a variety of transition metal catalysts withouthydrogenating the olefins into alkanes. Examples of these catalysts arePd, Fe, Co, Ni, Zn, and Cu containing catalysts.

Bases can react to neutralize the acid functionality that catalyzes ETLreactions. If enough base reacts with the ETL catalyst, the catalyst mayno longer be active toward oligomerization and may need to beregenerated. Bases include nitrogen containing compounds, particularlyammonia, amines, pyridines, pyroles, and other organic nitrogencontaining compounds. Metal hydroxide compounds such as lithium, sodium,potassium, cesium hydroxides and group IIA metal hydroxides maydeactivate the catalyst as well as carbonates of group IA and IIAmetals.

Bases can be removed from feedstock to an ETL reactor by, for example,contacting the feedstock stream with water. This can remove or decreasethe concentration of bases, such as amines, carbonates, and hydroxides.

Sulfur-containing compounds can deactivate ETL catalysts, particularlyif the catalysts are doped with transition metal compounds. Sulfur canirreversible bind to the catalyst or metal dopant to deactivate thecatalyst toward oligomerization. Organic sulfur compounds such asthiols, disulfides, thiolethers, thiophenes and others mercaptancompounds can be detrimental to the ETL catalyst.

Sulfur-containing compounds can be removed from feedstock to an ETLreactor by gas scrubbing, such as, for example, amine gas scrubbing.Amines can react with sulfur compounds (e.g., H₂S) to remove suchcompounds from gas streams. Other ways of removing sulfur compounds areby molecular sieves or hydrotreating. Examples of approaches forremoving sulfur-containing compounds from a gas stream are provided inNielsen, Richard B., et al. “Treat LPGs with amines,” HydrocarbonProcess 79 (1997): 49-59, which is entirely incorporated herein byreference.

The impact that certain non-ethylene gases can have on ETL catalysts issummarized in Table 1.

TABLE 1 Impact of non-ethylene gases on ETL catalyst Feedstock GeneralCatalyst Impact N₂ Inert Methane Inert CO₂ Inert H₂ Coke suppressant H₂OCoke suppressant but will deactivate catalyst in large quantities ethaneInert propylene Oligomerizes to gasoline butylene Oligomerizes togasoline acetylene Coke accelerator Dienes Coke accelerator CO Inert

Catalyst Regeneration

During the life cycle of a catalyst (e.g., ETL catalyst),carbon-containing material (e.g., petroleum coke) can deposit andaccumulate on the catalyst. Over time, such carbon-containing materialcan decrease the activity of the catalyst, and can even render thecatalyst incapable of converting a feedstock to a product. The catalystmay need to be changed or regenerated. There are various approaches forregenerating an ETL catalyst, such as oxidative regeneration andnon-oxidative regeneration.

In oxidative regeneration, an oxidizing agent (e.g., O₂) can be directedover the ETL catalyst at elevated temperatures to remove or decrease theconcentration of the carbon-containing material deposited on or over thecatalyst. This can occur by combusting the carbon-containing material.In some cases, prior to subjecting the catalyst to the oxidizing agent,the catalyst can be purged with and inert gas (e.g., He, Ar or N₂) toremove any volatile or residual hydrocarbon product on the catalystsurface. The catalyst can be subsequently exposed to the oxidizingagent. In some cases, the oxidizing agent is O₂ that can be provided byair.

In an example oxidative regeneration process, the process conditions andamount of air (or oxygen) can be predetermined to limit or control theamount of heat and water generated during the combustion process ofremoving the coke. The amount of O₂ can be limited to no more than 50%,40%, 30%, 20%, 10%, or 5% concentration. Air can be diluted with N₂ oranother gas that is inert toward combustion to dilute the concentrationto less than or equal to about 50%, 40%, 30%, 20%, 10% or 5%. Processconditions can be selected to keep the increase in temperature of theETL catalyst less than or equal to about 700° C., 650° C., 600° C., 550°C., or 500° C. during the regeneration. This can help prevent catalystdamage during the regeneration process. Oxidative regeneration reactorinlet temperatures can range from about 100° C. to 800° C., 150° C. to700° C., or 200° C. to 600° C. Inlet gas temperatures can be ramped fromlow to high temperatures to safely control the regeneration process.During oxidative regeneration, process gas pressures can range fromabout 1 bar (gauge, or “barg”) to 100 barg, 1 barg to 80 barg, or 1 bargto 50 barg.

In non-oxidative regeneration, hydrogen (H₂) and/or hydrocarbons can beused to regenerate the catalyst bed to improve catalyst activity of theETL catalyst. Hydrogen or hydrocarbon gases can be directed over thecatalyst bed at a temperature from about 100° C. to 800° C., 150° C. to600° C., or 200° C. to 500° C. This can aid in removing or decreasingthe concentration of carbon-containing material from the catalyst.

There are other approaches for reducing the concentration of catalystpoisons. Acetylene can be a poison at low levels. The acetylene and, insome cases, methyl acetylene, butadiene, propadiene and benzene, mayneed to be removed to some permissible levels. An approach fordecreasing the concentration of acetylene is to direct the acetylene toa hydrogenation reactor that hydrogenates the acetylene and butadiene toa mixture of ethylene and ethane as well as butane and/or butene.

The acetylene can be hydrogenated, for example, prior to being contactedwith the ETL catalyst. The acetylene hydrogenation reaction can bepracticed over a palladium-based catalyst, such as those used to convertacetylene to ethylene in conventional steam cracking (e.g., the PRICAT™series including models PD 301/1, PD 308/4, PD 308/6, PD 508/1, PD408/5, PD 408/7 and PD 608/1, which are commercially available astablets or spheres supported on alumina). A palladium-based catalyst caninclude one or more metals, including palladium. In some cases, theacetylene hydrogenation catalyst is a doped or modified version of acommercially available catalyst.

However, in some cases, applying an acetylene hydrogenation catalyst tothe OCM process that has been developed or optimized for another process(e.g., steam cracking separations and purification processes) can resultin operational issues and/or non-optimized performance. For example, insteam cracking, the acetylene conversion reactor can either be locatedon the front end (prior to cryogenic separations) or back end (aftercryogenic separations) of the process. In steam cracking, thesedifferences in running front end and back end typically have to do withthe ratio of hydrogen to acetylene present, the ethylene to acetyleneratio, and the non-ethylene olefin (e.g., butadiene) to acetylene ratio.All of these factors can impact the catalyst selectivity for formingethylene from acetylene, the lifetime and regeneration of the catalyst,green oil formation, specific process conditions for the reactor, andadditional hydrogen required for the reaction. These factors are alsodifferent between steam cracking versus OCM and/or ETL processes,therefore, provided herein is an acetylene hydrogenation catalyst thatis designed to be used in an OCM process.

In OCM and/or ETL implementations, the chemical components going intothe acetylene reactor can be different than for steam cracking. Forexample, OCM effluent can include carbon monoxide and hydrogen. Carbonmonoxide can be undesirable because it can compete with the acetylenefor the active sites on the hydrogenation catalyst and lead to loweractivity of the catalyst (i.e., by occupying those active sites).Hydrogen can be desirable because it is needed for the hydrogenationreaction, however that hydrogen is present in the OCM effluent in acertain ratio and adjusting that ratio can be difficult. Therefore, thecatalyst described herein provides the desired outlet concentrations ofacetylene, desired selectivity of acetylene conversion to ethylene,desired conversion of acetylene, desired lifetime and desired activityin OCM effluent gas. As used herein, “OCM effluent gas” generally refersto the effluent taken directly from an OCM reactor, or having firstundergone any number of further unit operations such as changing thetemperature, the pressure, or performing separations on the OCM reactoreffluent. The OCM effluent gas can have CO, H₂ and butadiene.

In some embodiments, the catalyst decreases the acetylene concentrationbelow about 100 parts per million (ppm), below about 80 ppm, below about60 ppm, below about 40 ppm, below about 20 ppm, below about 10 ppm,below about 5 ppm, below about 3 ppm, below about 2 ppm, below about 1ppm, below about 0.5 ppm, below about 0.3 ppm, below about 0.1 ppm, orbelow about 0.05 ppm.

The concentration of acetylene can be reached in the presence of carbonmonoxide (CO). In some embodiments, the feed stream entering theacetylene hydrogenation reactor contains at least about 10%, at leastabout 9%, at least about 8%, at least about 7%, at least about 6%, atleast about 5%, at least about 4%, at least about 3%, at least about 2%,or at least about 1% carbon monoxide.

When used in an OCM and/or ETL process, the acetylene hydrogenationcatalyst can have a lifetime of at least about 6 months, at least about1 year, at least about 2 years, at least about 3 years, at least about 4years, at least about 5 years, at least about 6 years, at least about 7years, at least about 8 years, at least about 9 years, or at least about10 years.

Another option can be to employ the use of a guard bed in front of theETL reactor (or reactor train comprising multiple ETL reactors). Theguard bed can enable the ETL reactor to preferentially coke out theacetylene. Can guard bed can coke relatively quickly and may need to beplaced in a lead-lag configuration so that one bed can be regeneratedwhile the other bed is being operated. The guard bed can contain acatalyst, and in some cases spent ETL catalyst, to perform preferentialcoking. The inlet temperature of guard bed can be lower than the inlettemperature for ETL, and the space velocity can be higher.

In an example, two guard beds are placed upstream of four or fiveparallel ETL reactor beds. The two guard beds are designed in a lead-lagconfiguration. The inlet temperature of the guard bed is about 40° C.,about 60° C., about 80° C., or about 100° C. lower than the inlet to theETL reactors and the space velocity is at least about 5×, at least about10×, at least about 20× or at least about 50× greater than the spacevelocity of the ETL reactors. The ETL reactors are on a schedule whereeach parallel reactor is regenerated and decoked every three weeks. Butthe guard bed is regenerated and decoked every 36 hours.

Catalyst Activators

The lifetime of a catalyst can be increased using activators. Activatorscan be used with catalysts of the present disclosure, such as ETLcatalysts. With the aid of activators of the present disclosure, thelifetime of a catalyst can be increased by at least about 10 hours, 20hours, 30 hours, 40 hours, 50 hours, 100 hours, 110 hours, 120 hours,130 hours, 140 hours, 150 hours, 160 hours, 170 hours, 180 hours, 190hours, 200 hours, 210 hours, 220 hours, 230 hours, 240 hours, 250 hours,300 hours, 350 hours, or 400 hours. Activators of the present disclosurecan be used to increase the lifetime of a catalyst by a factor of atleast about 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 3, 4, 5, 6,7, 8, 9, or 10 in relation to situations in which activators are notused. Activators can be molecules included in the process flow thatcontacts the catalyst and/or molecules or elements contained in thecatalyst itself (e.g., dopants). For example, Ga-doped ZSM-5 has anincreased lifetime (cycle lifetime and/or replacement lifetime) relativeto non-doped ZSM-5 (e.g., because the doped catalyst has a lowerselectivity for coke formation).

For example, the addition of water can enhance ETL catalyst lifetime bysuppressing coke formation. Coke formation can be suppressed by water byreacting with coke to form carbon monoxide and hydrogen. One of theattractive features from the OCM-ETL process is that water addition canbe optimized to have the maximum benefit for reducing coke formation inthe reactor. Water can be supplied in a concentration of at least about1%, 2%, 3%, 4%, 5%, 10%, 15%, 20%, 25%, or 30%. In some situations, theconcentration of water in feedstock into an ETL reactor is from 0% to30%, or 1% to 25%.

The addition of hydrogen in a feedstock stream into an ETL reactor canenhance ETL catalyst lifetime. Hydrogen gas (H₂) can be directed into anETL reactor and over an ETL catalyst, which can reduce the concentrationof carbon-containing material (e.g., coke) that may be present on thecatalyst and prohibit the deposition of carbon-containing material byhydrocracking reactions, for example, by breaking up larger moleculesthat may be eventually turned into coke and decrease catalyst activity.

ETL Processes and Operating Conditions

The present disclosure provides methods for operating ETL reactors toeffect a given or predetermined product distribution or selectivity. Theprocess conditions can be applied across a single or plurality of ETLreactors in series and/or parallel.

Hydrocarbon streams into or out of an ETL reactor can include variousother non-hydrocarbon material. In some cases, hydrocarbon streams caninclude one or more elements leached from an OCM catalyst (e.g., La, Nd,Sr, W) or ETL catalyst (e.g., Ga dopant)

Reactor conditions can be selected to provide a given selectivity andproduct distribution. In some cases, for catalyst selectivity towardsaromatics, an ETL reactor can be operated at a temperature greater thanor equal to about 300° C., 350° C., 400° C., 410° C., 420° C., 430° C.,440° C., 450° C., or 500° C., and a pressure greater than or equal toabout 250 pounds per square inch (PSI) (absolute), 200 PSI, 250 PSI, 300PSI, 350 PSI or 400 PSI. For catalyst selectivity towards jet or dieselfuel, an ETL reactor can be operated at a temperature greater than orequal to about 100° C., 150° C., 200° C., 210° C., 220° C., 230° C.,240° C., 250° C., or 300° C., and a pressure greater than or equal toabout 350 PSI, 400 PSI, 450 PSI, or 500 PSI. For catalyst selectivitytowards gasoline, an ETL reactor can be operated at a temperaturegreater than or equal to about 200° C., 250° C., 300° C., 310° C., 320°C., 330° C., 340° C., 350° C., or 400° C., and a pressure greater thanor equal to about 250 PSI, 300 PSI, 350 PSI, or 400 PSI.

In some cases, the operating conditions of an ETL process aresubstantially determined by one or more of the following parameters:process temperature range, weight-hourly space velocity (mass flow rateof reactant per mass of solid catalyst), partial pressure of a reactantat the reactor inlet, concentration of a reactant at the reactor inlet,and recycle ratio and recycle split. The reactant can be a (light)olefin—e.g., an olefin that has a carbon number in the range C2-C7,C2-C6, or C2-C5.

Temperatures used in a gasoline process can be from about 150 to 600°C., 220° C. to 520° C., or 270° C. to 450° C. Lower temperature canresult in insufficient conversion while higher temperatures can resultin excessive coking and cracking of product. In an example, the WHSV canbe between about 0.5 hr⁻¹ and 3 hr⁻¹, partial pressures can be betweenabout 0.5 bar (absolute) and 3 bar, and concentrations at the reactorinlet can be between about 2% and 30%. Higher concentrations can yielddifficult-to-manage temperature excursions, while lower concentrationscan make it difficult to achieve sufficiently high partial pressures andseparation of the products. A process can achieve longer catalystlifetime and higher average yields when a portion of the effluent isrecycled. The recycle can be determined by a recycle ratio (e.g., volumeof recycle gas/volume of make-up feed) and the post-reactor vapor-liquidsplit which determines the composition of the recycle stream. There maybe several degrees of freedom to the recycle split, but in some casesthe composition of the recycle stream may be important, which isachieved by post-reactor separation (i.e., typical carbon number/boilingpoint range that is recycled vs. the carbon number/boiling point rangesthat are removed by product and/or secondary process streams.

To achieve longer average chain lengths and to avoid cracking ofelongated chains such as those found in jet fuel and distillates, ETLcan be performed at reactor operating temperatures from about 150° C. to500° C., 180° C. to 400° C., or 200° C. to 350° C. The slower kineticsmay suggest a lower minimum WHSV of about 0.1 hr⁻¹. Longer chain lengthsmay be favored by high partial pressures, so the upper end forjet/distillates may be higher than for gasoline, in some cases as highas about 30 bar (absolute), 20 bar, 15 bar, or 10 bar.

More consistent production of aromatics can be achieved at hightemperature ranges, such as a temperature up to about 200° C., 250° C.,300° C., 350° C., 400° C., 450° C., or 500° C. In an adiabatic or evenin a pseudo-isothermal reactor, the ethylene/olefin feed can be dilutedby an inert gas (e.g., N₂, Ar, methane, ethane, propane, butane or He).The inert gas can serve to moderate the temperature increase in thereactor bed, and maintain and stabilize contact time. The olefinconcentration at the reactor inlet can be less than about 50%, 40%, 30%,20%, or 10%. In some cases, the higher the molar heat capacity of thediluent, the higher the inlet concentration of olefins can be to achievethe same temperature rise.

The following is a list of suitable compounds that may be found insignificant quantities in the process. Such compounds are listed in theorder of increasing heat capacity: nitrogen, carbon dioxide, methane,ethane, propane, n-butane, iso-butane.

In some cases, a continuous process for making mixtures of hydrocarbonsfrom (light) olefins by oligomerization comprises feeding olefiniccompounds to a reaction zone of an ETL reactor. The reactor zone cancontain a heterogeneous catalyst. One or more inert gases can be co-fedto the reactor inlet, making up from about 50% (volume %) to 99%, 60% to98%, or 70% to 98% of the feedstock. The mixture can be comprised atleast one of the following compounds: nitrogen, carbon dioxide, methane,ethane, propane, n-butane, iso-butane. The process (e.g., ETL reactor)temperature can be between about 150° C. and 600° C., 180° C. and 550°C., or 200° C. and 500° C. The partial pressure of olefins in the feedcan be between about 0.1 bar (absolute) to 30 bar, 0.1 bar to 15 bar, or0.2 bar to 10 bar. The total pressure can be between about 1 bar(absolute) to 100 bar, 5 bar to 50 bar, or 10 bar to 50 bar. The weighthourly space velocity can be between about 0.05 hr⁻¹ to 20 hr⁻¹, 0.1hr⁻¹ to 10 hr⁻¹, or 0.1 hr⁻¹ to 5 hr⁻¹.

An effluent or product stream from an ETL reactor can be characterizedby low water content. For example, an ETL product stream can compriseless than 60 wt %, 56 wt %, 55 wt %, 50 wt %, 45 wt %, 40 wt %, 39 wt %,35 wt %, 30 wt %, 25 wt %, 20 wt %, 15 wt %, 10 wt %, 5 wt %, 3 wt %, or1 wt % water.

In some cases, at least a portion of the reactor effluent is recycled tothe reactor inlet. As an alternative, at most a portion of the reactoreffluent is recycled to the reactor inlet. The volumetric recycle ratio(i.e., flow rate of the recycle gas stream divided by flow rate of themake-up gas stream (i.e., fresh feed)) can be between about 0.1 and 30,0.3 and 20, or 0.5 and 10.

A continuous process for making mixtures of hydrocarbons for use asgasoline can comprise feeding olefinic compounds to a reaction zone ofan ETL reactor. The ETL reactor can include a catalyst that is selectedfor gasoline production, as described elsewhere herein. The processtemperature can be between about 200° C. and 600° C., 250° C. and 500°C., or 300° C. and 450° C. The partial pressure of olefins in the feedcan be between about 0.1 bar (absolute) to 10 bar, 0.3 bar to 5 bar, or0.5 bar to 3 bar. The total pressure can be between about 1 bar(absolute) to 100 bar, 5 bar to 50 bar, or 10 bar to 50 bar. The weighthourly space velocity can be between about 0.1 hr⁻¹ to 20 hr⁻¹, 0.3 hr⁻¹to 10 hr⁻¹, or 0.5 hr⁻¹ to 3 hr⁻¹.

For products in the distillate range (e.g., C₁₀₊ molecules, which canexclude gasoline in some cases), the catalyst composition can beselected as described elsewhere herein. The process temperature can bebetween about 100° C. and 600° C., 150° C. and 500° C., or 200° C. and375° C. The partial pressure of olefins in the feed can be between about0.5 bar (absolute) to 30 bar, 1 bar to 20 bar, or 1.5 bar to 10 bar. Thetotal pressure can be between about 1 bar (absolute) to 100 bar, 5 barto 50 bar, or 10 bar to 50 bar. The weight hourly space velocity can bebetween about 0.05 hr⁻¹ to 20 hr⁻¹, 0.1 hr⁻¹ to 10 hr⁻¹, or 0.1 hr⁻¹ to1 hr⁻¹.

For products comprising mixtures of hydrocarbons substantially comprisedof aromatics, the catalyst composition can be selected as describedelsewhere herein. The process temperature can be between about 200° C.and 800° C., 300° C. and 600° C., or 400° C. and 500° C. The partialpressure of olefins in the feed can be between about 0.1 bar (absolute)to 10 bar, 0.3 bar to 5 bar, or 0.5 bar to 3 bar. The total pressure canbe between about 1 bar (absolute) to 100 bar, 5 bar to 50 bar, or 10 barto 50 bar. The weight hourly space velocity can be between about 0.05hr⁻¹ to 20 hr⁻¹, 0.1 hr⁻¹ to 10 hr⁻¹, or 0.2 hr⁻¹ to 1 hr⁻¹.

The ETL process can generate a variety of long-chain hydrocarbons,including normal and isoparaffins, napthenes, aromatics and olefins,which may not be present in the feed to the ETL reactor. The catalystcan deactivate due to the deposition of carbonaceous deposits (“coke”)on the surfaces of the catalyst. As the deactivation progresses, theconversion of the process changes until a point is reached when thecatalyst can be regenerated.

In some cases, in the early stages of a reaction cycle, the productdistribution can contain large fractions of aromatics and short-chainedalkanes. Later stages can feature increased fractions of olefins. Allstages can feature various amounts isoparaffins, n-paraffins,naphthenes, aromatics, and olefins, including olefins other than feedolefins. The change in selectivity with time can be exploited byseparating products. For example, the aromatics-rich effluentcharacteristic of the early stages of a reaction cycle may be readilyseparated from the effluent of a catalyst bed in a later stage of itscycle. This can result in high selectivities of individual products. Anexample of how the product distribution can change over time is given inFIG. 5, which is for a Ga-ZSM-5 catalyst.

The ETL process can generate various byproducts, such ascarbon-containing byproducts (e.g., coke) and hydrogen. The selectivityfor coke can be on the order of at least about 1%, 2%, 3%, 4%, or 5%over the course of an ETL process. Hydrogen production can vary withtime, and the amount of hydrogen generated can be correlated witharomatics production.

In some cases, the time-averaged product of the process can yield aliquid with a composition that meets the specification of reformulatedgasoline blendstock for oxygen blending (RBOB). In some cases, RBOB hasat least about an 93 octane rating using the (RON+MON)/2 method, hasless than about 1.3 vol % benzene as measured by ASTM D3606, has lessthan about 50 vol % aromatics as measured by ASTM D5769, has less thanabout 25 vol % olefins as measured by ASTM D1319 and/or D6550, has lessthan 80 ppm(wt) sulfur as measured by ASTM D2622, or any combinationthereof. Such liquid can be employed for use as fuel or other combustionsettings. This liquid can be partially characterized by the content ofaromatics. In some cases, this liquid has an aromatics content from 10%to 80%, 20% to 70%, or 30% to 60%, and an olefins content from 1% to60%, 5% to 40%, or 10% to 30%. Gasoline can comprise about 60% to 95%,70% to 90%, or 80-90% of such liquid, with the remainder in some casesbeing an alcohol, such as ethanol.

In some situations, an ETL process is used to generate a mixture ofhydrocarbons from light olefin compounds (e.g., ethylene). The mixturecan be liquid at room temperature and atmospheric pressure. The processcan be used to form a mixture of hydrocarbons having a hydrocarboncontent that can be tailored for various uses. For example, mixturestypically characterized as gasoline or distillate (e.g., kerosene,diesel) blend stock, or aromatic compounds, can contribute at least 30%,40%, 50%, 60%, or 70% by weight to the final fuel product.

The product selectivity of the ETL process can change with time. Withsuch changes in selectivity, the product can include varyingdistributions of hydrocarbons. Separations units can be used to generatea product distribution which can be suitable for given end uses, such asgasoline.

Products of ETL processes of the present disclosure can include otherelements or compounds that may be leached from reactors or catalysts ofthe system (e.g., OCM and/or ETL reactors). Examples of OCM catalystsand the elements comprising the catalyst that can be leached into theproduct can be found in U.S. patent application Ser. No. 13/689,611 orU.S. Provisional Patent Application 61/988,063, each of which isincorporated by reference in its entirety. Such elements can includetransition metals and lanthanides. Examples include, but are not limitedto Mg, La, Nd, Sr, W, Ga, Al, Ni, Co, Ga, Zn, In, B, Ag, Pd, Pt, Be, Ca,and Sr. The concentration of such elements or compounds can be at leastabout 0.01 parts per billion (ppb), 0.05 ppb, 0.1 ppb, 0.2 ppb, 0.3 ppb,0.4 ppb, 0.5 ppb, 0.6 ppb, 0.7 ppb, 0.8 ppb, 0.9 ppb, 1 ppb, 5 ppb, 10ppb, 50 ppb, 100 ppb, 500 ppb, 1 part per million (ppm), 5 ppm, 10 ppm,or 50 ppm as measured by inductively coupled plasma mass spectrometry(ICPMS).

The composition of ETL products from a system can be consistent overseveral cycles of catalyst use and regeneration. A reactor system can beused and regenerated for at least about 10, 20, 30, 40, 50, 60, 70, 80,90, or 100 cycles. After a number of regeneration cycles, thecomposition of the ETL product stream can differ from the composition ofthe first cycle ETL product stream by no more than about 0.1%, 0.2%,0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4%, 5%, 6%, 7%,8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%.

ETL Process Design

The present disclosure provides various approaches for designing an ETLprocess. In the oligomerization of C₂H₄, a range of hydrocarbons can beformed, including C₂H₆ and CH₄, as well as H₂. The shorter chainhydrocarbons (e.g., C1-C4) and hydrogen in the product stream can beseparated from the C₅₊ liquid fraction. A fraction of the process streamcontaining these lighter molecular weight products can be combined, orrecycled, with incoming C₂H₄ feed stream, as shown in FIG. 6. In thisfigure, product stream 605 can be separated, for instance by acondenser/phase separator 606. The gas stream 608 from thecondenser/phase separator can be partially recovered 609 and partiallyrecycled 610 back into the reactor 604 for further contacting with thecatalyst. The OCM reactor effluent 601, which can have been treatedand/or compressed, is then routed to the treatment unit 602 which maycomprise of a water removal unit, or any other purification unit. Thetreated ETL feed 603 reacts in the ETL reactor 604 to generate netliquid product 607 from the condenser and phase separator unit. Thecondenser and phase separator unit also sends a recycle 608 back to theETL reactor inlet.

Recycling can have various benefits, such as: 1) further reaction ofshorter chain hydrocarbon products to form higher molecular weightproducts, 2) increasing catalyst lifetime, and 3) diluting the C₂H₄ feedstream to control the reactor process conditions of reactantconcentration and adiabatic temperature rise.

At the same C₂H₄ WHSV, the conversion of a reactor inlet streamcontaining recycle can have a higher yield of liquids production (C₅₊),particularly C₅₊ condensable at a temperature of around 0° C., than thatof a reactor inlet stream without recycle products (see FIGS. 7 and 8).The use of recycle can also increase catalyst lifetime, as measured bytime-on-stream and grams C₂H₄ converted per grams of catalyst. Recycleratios and g liquid condensed at about 0° C. are shown in Table 2.

FIG. 7A shows liquid phase mass balance for C₂H₄ conversion by usingsingle pass reactor. FIG. 7B shows liquid phase mass balance for C₂H₄conversion by using a reactor with 5:1 recycle. The reactors areoperated at a pressure of about 30 bar, a weight hourly space velocity(WHSV) of about 0.7 h⁻¹, and an inlet temperature of about 350° C. Theamounts of various hydrocarbons produced ranges from 0% to 100% forvarious ethylene conversions with paraffins 700, isoparaffins 705,olefins 710, napthenes 715, aromatics 720 and C₁₂+ compounds 725 beingshown. FIG. 8 is a plot showing increasing C₅₊ yield (liquid condensedat about 0° C.) with increasing recycle. The reaction conditionsincluded a WHSV=0.27 h⁻¹; reactor inlet C₂H₄ mol %=2; T_(peakbed)=315°C.; total pressure 300 psi (gauge);

TABLE 2 Reactor conditions characterized by product stream data shown inFIG. 8, including recycle ratios, process inlet C₂H₄ mol %, reactorinlet C₂H₄ mol % and grams of liquid condensed per grams of C₂H₄ fed.Process inlet Reactor inlet g liquid condensed Recycle ratio C₂H₄ mol %C₂H₄ mol % per g C₂H₄ fed 9:1 20 2 0.76 4:1 10 2 0.66 2:1  6 2 0.54 0:1 2 2 0.15 (no recycle)

In some cases, an inlet feed stream that is diluted with recycle productstream allows for a smaller adiabatic temperature rise in the reactorand reduced C₂H₄ concentration into the reactor. A lower adiabatictemperature rise, and therefore peak reactor temperature, can alter theeffluent product stream composition. Higher peak reactor temperatures,for instance, can increase the yield and selectivity of aromaticproducts.

Different amounts of ethylene in an ETL product stream can be recycled.In some cases, at least about 5%, 10%, 15%, 20%, 25%, 30%, 25%, 40%,45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%,99%, or 100% of ethylene in an ETL product stream is recycled. In somecases, at most about 5%, 10%, 15%, 20%, 25%, 30%, 25%, 40%, 45%, 50%,55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%of ethylene in an ETL product stream is recycled.

An ETL process can be characterized by a single pass conversion orsingle pass conversion of C₂₊ compounds to C₃₊ compounds of at least10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%,80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, 99.9%, or 99.99%.

ETL Process Feedstock

The feedstock to an ETL reactor can have an effect on the productdistribution out of the ETL reactor. The product distribution can berelated to the concentration of olefins into the ETL reactor, such asethylene, propylene, butene(s) and pentene(s). The feedstockconcentration can impact ETL catalyst efficiency. A feedstock having anolefin concentration that is greater than or equal to about 5%, 10%,15%, 20%, 25%, 30%, or 40% can be efficient at generating highermolecular weight hydrocarbons. In some cases, the optimum olefinconcentration can be less than about 80%, 85%, 75%, 70% or 60%. The ETLfeedstock can be characterized based on the ethylene to ethane molarratio of the feedstock, which can be at least about 2:1, 3:1, 4:1, 5:1,6:1, 7:1, or 8:1.

The presence of other C₂₊ compounds and non-C₂₊ impurities (e.g., CO,CO₂, H₂O and H₂) can have an impact on ETL selectivity and/or productdistribution. For instance, the presence of acetylene and/or dienes in afeedstock to an ETL reactor can have a significant impact on ETLselectivity and/or product distribution, since acetylene may be adeactivator and coke accelerator.

Separations for ETL

Separations for ETL processes of the present disclosure can be carriedout in three places within the ETL scheme: before the ETL reactor,within the ETL reactor and downstream of the ETL reactor. In each ofthese three places, different separations technologies can be employed.

To process the ETL reactor feed, traditional gas separations equipmentcan be used. These separations may include pressure swing adsorption,temperature swing adsorption and membrane-based separation. The reactorfeed could also be augmented by utilizing cryogenic separationsequipment found in a traditional midstream gas plant.

To make changes to the composition within the reactor, different typesof catalyst can be co-mixed or layered within the catalyst bed orreactor vessel. Different types of zeolite catalysts (for example aZSM-5 and a SAPO 34 in a 60%/40% mixture or in a 50%/50% mixture) couldcreate different hydrocarbon profiles at the reactor vessel outlet. Alsowithin this vessel, there could be a combination of multiple beds withappropriate quenches built in to affect the final product composition.

To separate the reactor outlet mixtures, a combination of flashseparation, hydrogenation, isomerization and distillation can be used.Flash separation will remove most of the light fractions of thehydrocarbon liquid product. This can affect product qualities like ReidVapor Pressure. Hydrogenation, isomerization and distillation can thenbe used, much like traditional refining processes, to create a fungibleproduct.

ETL separation can be implemented upstream of an ETL reactor. Membranesused in conjunction with the ETL process can be used on the processfeedstock to enrich components prior to directing the feedstock to theETL reactor. Ethylene may be a component that can be enriched. Othercomponents of the feedstock may also be enriched, such as H₂ and/or CO₂.In some cases, CO may be rejected.

For example, CO in the feedstock may be a catalyst poison. CO can beremoved prior to directing the feedstock to the ETL reactor. Hydrogenmay be an advantageous species to have in the feedstock because it canreduce coking rates, thus lengthening on-stream time between de-cokecycles.

In some cases, a membrane separation unit upstream of an ETL reactor maybe employed. The membrane unit can remove at least about 20%, 30%, 40%,50% or 60% of one component, or increase the amount of ethylene from atleast about 1%, 2%, 3%, 4% or 5% to at least about 10%, 15%, 20%, 30%,or 40%.

As another example, ethylene can be enriched using a membrane that has acertain chemical affinity to ethylene. For oxygen separations membranes,cobalt can be used within the membranes to chemically pull oxygenthrough the membranes. Chemically-modified membranes can be used toeffect such separation.

Another technique that can be employed for upstream separation ispressure swing adsorption (PSA). Pressure swing adsorption can be usedto remove substantially all of a certain poison, or enrich ethylene tonear purity. In some cases, PSA may be used in place of, or in addition,membrane. The PSA unit can include at least 2, 3, 4, 5, 6, 7, 8, 9, or10 vessels that contain an adsorbent. This adsorbent may be acombination of zeolites, molecular sieves or activated carbon, forexample. Each vessel can contain one or more adsorbents co-mixed orlayered within the vessel. An example of a PSA unit is shown in FIG. 9.The system shown in FIG. 9 is an activated carbon based system 900 toseparate oxygen from nitrogen. The system comprises carbon molecularsieves 901 which receive gas streams 902 to be treated. Part of the gasstreams can be released as off gas 903. Treated gas 904 can compriseproduced nitrogen. The activated carbon system can comprise carbonparticles 905, which can interact with N₂ molecules 906 and O₂ molecules907. The carbon particles can have sizes for example from about 1 toabout 20 micrometers, with a pore size from about 0.4 nanometers toabout 25 nanometers.

The PSA units can operate at ETL reactor pressures (e.g., 5-50 bar) andblow down to atmospheric pressure. Activated carbon, 3A, 4A, 5Amolecular sieves and zeolites can be used in these beds. The vessels canbe operated such that the wanted gases (e.g., ethylene) pass through thebeds at high pressure, and unwanted gases (e.g., CO, CO₂ or methane) areblown down out of the bed at low pressure.

As an example, the specific choice of sorbent can determine the speciesthat passes through at high pressure or is exhausted at low pressure. Insome cases, a PSA can use layered sorbents, such as to effect methaneand nitrogen separation. Such layering within the bed allows methane tobe the blow down gas, rather than nitrogen.

PSA technology can also be used in other situations. Multiple beds canbe used in series to further enrich the wanted process gases. PSA unitswith at least 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, or 30 vessels may beemployed. The PSA can be operated at high frequencies, which can furtherpromote better separation.

Another separation technique that can be employed for use with ETL istemperature swing adsorption (TSA). In TSA, temperature changes are usedto effect separation. TSA can be used to separation hydrocarbonsmixtures after the ETL reactor. When gas mixtures are close to changingphases, TSA can be helpful in removing the heavy fraction from the lightfraction.

The present disclosure also provides in-reactor separations (productaugmentation) approaches. Some of the separations goals can be achievedwithin the catalyst bed, or within the reactor vessel itself, usingreactive separations, for example. In reactive separation, a firstmolecule can be reacted to form a larger or smaller molecule that may beseparated from a given stream.

In some cases, gas phase ethylene can be condensed to a liquid viareaction. This augmentation can take two forms within the catalyst bed:it can augment the product to bring it to within a given specification,or it can augment the product to remove downstream equipment. As anexample of bringing products into specification, a hydrogenationcatalyst can be co-mixed or layered within the bed, or as a second bedwithin a reactor vessel. This catalyst can utilize the availablehydrogen to decrease the olefin content of the final product. Sincefungible gasoline (and many other products) can have an olefinspecification to prevent gumming, this in situ separation can remove alarge amount of olefin content from the resulting liquid, bringing it towithin a given specification.

A co-mixed bed with multiple types of different zeolite can affect theoverall product composition. For example, a low-aromatic producingcatalyst can be added in an 80%/20% mixture to a typical ETL catalyst.The resulting product stream can be lower in aromatics, and can bring anoff-spec product to within a given specification.

As another approach, a downstream (in vessel) isomerization bed can beused to remove unwanted isomers, like durene. Hydrocarbon compounds ofany appropriate carbon number, such as hydrocarbon compounds with fouror more carbon atoms (C₄₊ compounds), can be isomerized. If a downstreamunit is necessary to isomerize components like durene, or removecomponents, such as high boiling point components, an in-bed reactorapproach can be employed.

In some situations, a mixture of zeolites that have been augmented via aprocess may also provide for a desirable separation. Such mixture can beused to provide for product augmentation.

The present disclosure also provides separations approaches downstreamof an ETL reactor. Downstream separations equipment for an ETL processcan be similar to equipment employed for use in refineries. In somecases, downstream unit operations can include flash separation,isomerization, hydrogenation and distillation, which can aid in bringingthe final product to within a given specification.

Isomerization equipment can convert unwanted iso-durene into a morevolatile form. Hydrogenation equipment can reduce the amount ofolefins/aromatics in the final product. Distillation can separatematerial on the basis of boiling point. These units can be readily usedto create a product having a product distribution as desired.

Isomerization equipment can be used to upgrade the octane rating of ahydrocarbon product composition. For example, n-hexane can be isomerizedto i-hexane. N-pentane (62 octane) can be isomerized to 2-methyl-butane(93 octane). Hexane (25 octane) can be isomerized to 2-methyl-pentane(73 octane).

Alkylation and dimerization units can upgrade lighter fractions, such asbutanes, into more valuable, higher octane products. If the ETL reactorproduces a large amount of butenes compared to butanes, thendimerization can be used to convert the butene into isooctene/isooctane.

A catalytic reformer unit can upgrade light naphtha fraction to areformate. This unit works by combining molecules and producinghydrogen. If well-placed, the hydrogen produced in this unit can beutilized in a downstream unit.

Depending on the size and scale of the ETL reactor, vacuum distillationcan be employed to further refine the hydrocarbon product outputted bythe ETL reactor. If such products are valuable as lubricants, oils andwaxes, then the extra step to vacuum distill these products can beadvantageous. In some cases, the amount of heavy components produced inthe ETL reactor is less than 20%, 15%, 10%, 5% or 1%, but the valuegenerated out of those products can be substantial.

Another approach for separating hydrocarbons is cryogenic separation.Such separation can be used to capture C4 and C₅₊ compounds from an ETLreactor effluent product stream. In some cases, a cryogenic separationunit can include a cold box that may not use traditional deep cryogenictemperatures and may not require traditional unit operations ofdemethanizer and deethanizer. Such cryogenic separation unit may notproduce high purity methane, ethane, or propane products. However, itmay produce a mixed (in some cases primarily methane) stream withimpurity ethane, propane, other light hydrocarbons and inert gases thatare acceptable for use in other settings, such as reinjection topipeline gas, as residue gas, or used to meet fuel requirements forpower plants or feedstocks for syngas plants for the production ofmethanol or ammonia.

In some examples, a cryogenic separation unit can operate at atemperature from about −100° C. to −20° C., −90° C. to −40° C., or −80°C. to −50° C. Such temperatures can be obtained through methods that usethe turboexpansion of high pressure pipeline natural gas orturboexpansion of moderate pressure high methane content feedstock gas,which may be typical of OCM reactor inlet requirements where additionalcooling may be accomplished using traditional process plantrefrigeration loops, including propane refrigeration or other mixedrefrigerants.

In some cases, there may be substantial recovery of pressure-reducedpower by coupling of turboexpander and residue gas compressors dependingon final destination and usage of lighter nonreacted and unrecoverablehydrocarbons and other components.

In an example OCM-ETL system, gas is expanded and/or additionalrefrigeration cooled and fed to a cryogenic cold box unit, where heat isexchanged with multiple downstream product streams. It can then be fedto an OCM reaction and heat recovery section. Pressure can be increasedthrough multiple process gas compressors, then heated for ETL and thenETL reaction section. Unrefrigerated liquids recovery can beaccomplished using air and cooling water utilities before the productgas enters the cryogenic cold box unit, where it is cooled, pressurereduced for cooling effects, and additional condensed liquids removedvia a liquid-liquid separator. Separated liquids can reenter thecryogenic cold box unit, where they are heat exchanged prior to beingfed to a depropanizer unit which removes impurity propane and otherlight compounds from final C₄₊ product. Separated gas from theliquid-liquid separator also renter the cryogenic cold box unit wherethey are heat exchanged prior to being mixed with depropanizer overheadproduct gas and then fed to residue gas compressors based on finalresidue gas users. The depropanizer reflux condensation is also providedby sending this gas stream through the cryogenic cold box unit.

In some cases, a debutanizer column can be installed with bottomsproduct from depropanizer as feed. Its use can be to provide RVP controlof final C₄₊ product. In some cases, RVP control may be precluded, otherpurifications or chemical conversions may be employed.

ETL Reactor Feedstock

Olefin-to-liquids (e.g., ETL) processes of the present disclosure can beperformed using feedstocks comprising one or more olefins, such as pureethylene or diluted ethylene. Ethylene can be mixed with non-hydrocarbonmolecules or other hydrocarbons, including olefins, paraffins,naphthenes, and aromatics. When a feedstock comprising these materialsis directed over an ETL catalyst, such as a zeolite catalyst bed attemperatures of at least about 150° C., 200° C., 250° C., or 300° C.,the reactants can oligomerize to form a combination of longer chainisomers of olefins and paraffins, naphthenes, and aromatics. The productslate can include hydrocarbons with carbon numbers between 1 and 19(i.e., C₁-C₁₉).

The concentration of ethylene (or other olefin(s)) can be changed byadjusting the partial pressure of ethylene (or other olefin(s)) atconstant total pressure by dilution with an inert gas, such as nitrogenor methane, or by adding an inert gas to increase the total pressurewhile keeping the partial pressure of ethylene constant. A change inconcentration due to changes in the total pressure may not lead tosignificant variations in the process unless the system is operated inan adiabatic mode, in which temperature spikes introduce additionalvariability.

In an isothermal reactor operation, a change in concentration viaadjustments in the partial pressure of ethylene can prompt increases inliquid content and reduction of olefins at the benefit of paraffins andaromatics. The changes observed in product slate and liquid formationcan depend on the temperature regime and the class of molecules formedin that regime (i.e., isoparaffins and aromatics at temperatures belowor above about 400° C., respectively). For example, increasing theconcentration of ethylene from 5% to 15% at a constant total pressure of1 bar and a WHSV of 1 g ethylene/g catalyst/hour can result in a changefrom 15% to 45% liquids at 300° C.

As the temperature increases, the starting liquid percent increases, yetthe net change upon an increase in concentration diminishes. Forexample, at 390° C., increasing the concentration of ethylene from 5% to15% at a constant total pressure of 1 bar can result in a change of 45%to 65% liquids. The composition of the product can also change withincreasing concentration of ethylene. The trend is uniform withtemperature: as the concentration increases, the content of olefinsdecreases at the benefit of paraffin isomers, naphthenes, and aromatics.As the temperature is increased to at least about 300° C., 350° C., 400°C. or 450° C. and the product slate is heavily aromatic, changes in thepartial pressure of ethylene may not change the product slate but cancause a decrease in the liquid content.

In an adiabatic operation, the concentration of ethylene may result in achange in the liquid and product slate, which is coupled to thevariations in temperature zones across the reactor bed. In this mode,the rate of heat transfer from a differential volume unit of the reactorbed is a function of the heat capacity of the catalyst and gaseousmolecules in the stream—in particular the inert species. Thus,decreasing the concentration of ethylene helps increase the heatdissipation and the temperature in the volume unit. In general, as theconcentration of ethylene is increased, the temperature in the bed canincrease and the content of aromatics and net liquids can also increaseat the expense of paraffins, isoparaffins, olefins, and naphthenes. Whenthe temperature reaches at least about 300° C., 350° C., 400° C. or 450°C., the net amount of liquid can decrease as cracking of the liquidmolecules becomes more prevalent.

In some cases, the addition of other hydrocarbons from a recycle,refinery or midstream operation combined with the ethylene feedstock mayhave a positive effect on the formation of liquids. The ETL process isan oligomerization reaction, in which hydrocarbons are combined to formlonger chain hydrocarbons. Thus, introducing hydrocarbons with C₃₊olefin chain length in addition to the C₂ ethylene promotes theformation of liquid. As long as the reaction conditions or inherentnature of the catalyst itself precludes cracking (β-scission) of thehydrocarbon, the addition of longer chain hydrocarbons in the feed mayyield an oligomerized product that is the sum of the two molecules. Inother words, the barrier to producing longer chain molecules is reducedby minimizing the number of molecular units at the start of the reactor(C₂+C₂+C₂+C₂=C₈ vs. C₂+C₆=C₈).

Gas molecules that can be co-fed with ethylene can come from a recyclestream, natural gas liquids, midstream operations, or refinery effluentscomprising ethane, propylene, propane, butene isomers, and butaneisomers, and other C₄₊ olefins. The general product slate can be more orless unchanged by introducing propylene, isobutene, and trans-2-butene(with similar expectations for other butene isomers). At a constantvolumetric flowrate of hydrocarbon species, substitution of a longerchain hydrocarbon for a shorter chain hydrocarbon (e.g., propylenereplacing ethylene) can result in a higher content of liquid formed.

For example, at T=300° C. with 0.15 bar partial pressure of hydrocarbon,1 bar total pressure, a 50:50 mixture of propylene or isobutene withethylene increases the liquid yield by 10%-20% in comparison to a pureethylene feedstock (an increase in liquids can be due to an increase inliquid (C₅₊) isoparaffins). When the temperature is 390° C. or higherand aromatic molecules are the dominant product species, the impact ofhydrocarbon length has less effect on the liquid formation. Regardless,we have found that the presence of propylene or isobutene in the feedpromotes the formation of liquids (aromatics) to an extent (a fewpercentage points) that is greater than using an isolated pure feeds.

Additional paraffins (e.g., ethane, propane, and butane) can influencemay impact an ETL reaction and product distribution. The introduction ofn-paraffins may yield an increase in isoparaffin content due toisomerization of the molecules on the acid zeolite catalyst. As thetemperature and rate of dehydrogenation increases, the impact ofintroduced paraffins may mirror the behavior observed by adding olefins.Co-feeding C₅₊ hydrocarbons with ethylene may also improve the liquidconversion performance of the ETL process due to the nature of theoligomerization process.

Oxidative Coupling of Methane (OCM) Processes

In an OCM process, methane (CH₄) reacts with an oxidizing agent over acatalyst bed to generate C₂₊ compounds. For example, methane can reactwith oxygen over a suitable catalyst to generate ethylene, e.g., 2CH₄+O₂→C₂H₄+2 H₂O (See, e.g., Zhang, Q., Journal of Natural Gas Chem.,12:81, 2003; Olah, G. “Hydrocarbon Chemistry”, Ed. 2, John Wiley & Sons(2003)). This reaction is exothermic (ΔH=−67 kcals/mole) and hastypically been shown to occur at very high temperatures (>700° C.).Experimental evidence suggests that free radical chemistry is involved.(Lunsford, J Chem. Soc., Chem. Comm., 1991; H. Lunsford, Angew. Chem.,Int. Ed. Engl., 34:970, 1995). In the reaction, methane (CH₄) isactivated on the catalyst surface, forming methyl radicals which thencouples in the gas phase to form ethane (C₂H₆), followed bydehydrogenation to ethylene (C₂H₄). Several catalysts have shownactivity for OCM, including various forms of iron oxide, V₂O₅, MoO₃,CO₃O₄, Pt—Rh, Li/ZrO₂, Ag—Au, Au/Co₃O₄, Co/Mn, CeO₂, MgO, La₂O₃, Mn₃O₄,Na₂WO₄, MnO, ZnO, and combinations thereof, on various supports. Anumber of doping elements have also proven to be useful in combinationwith the above catalysts.

Since the OCM reaction was first reported over thirty years ago, it hasbeen the target of intense scientific and commercial interest, but thefundamental limitations of the conventional approach to C—H bondactivation appear to limit the yield of this attractive reaction underpractical operating conditions. Specifically, numerous publications fromindustrial and academic labs have consistently demonstratedcharacteristic performance of high selectivity at low conversion ofmethane, or low selectivity at high conversion (J. A. Labinger, Cat.Lett., 1:371, 1988). Limited by this conversion/selectivity threshold,no OCM catalyst has been able to exceed 20-25% combined C₂ yield (i.e.ethane and ethylene), and more importantly, all such reported yieldsoperate at extremely high temperatures (>800° C.). Catalysts andprocesses have been described for use in performing OCM in theproduction of ethylene from methane at substantially more practicabletemperatures, pressures and catalyst activities. These are described inU.S. Patent Publication Nos. 2012/0041246, 2013/0023079, and2013/165728, and U.S. patent application Ser. Nos. 13/936,783 and13/936,870 (both filed Jul. 8, 2013), the full disclosures of each ofwhich is incorporated herein by reference in its entirety for allpurposes.

An OCM reactor can include a catalyst that facilitates an OCM process.The catalyst may include a compound including at least one of an alkalimetal, an alkaline earth metal, a transition metal, and a rare-earthmetal. The catalyst may be in the form of a honeycomb, packed bed, orfluidized bed. In some embodiments, at least a portion of the OCMcatalyst in at least a portion of the OCM reactor can include one ormore OCM catalysts and/or nanostructure-based OCM catalyst compositions,forms and formulations described in, for example, U.S. PatentPublication Nos. 2012/0041246, 2013/0023709, 2013/0158322, 2013/0165728,and pending U.S. application Ser. No. 13/901,309 (filed May 23, 2013)and Ser. No. 14/212,435 (filed Mar. 14, 2014), each of which is entirelyincorporated herein by reference. Using one or more nanostructure-basedOCM catalysts within the OCM reactor, the selectivity of the catalyst inconverting methane to desirable C₂₊ compounds can be about 10% orgreater; about 20% or greater; about 30% or greater; about 40% orgreater; about 50% or greater; about 60% or greater; about 65% orgreater; about 70% or greater; about 75% or greater; about 80% orgreater; or about 90% or greater.

An OCM reactor can be sized, shaped, configured, and/or selected basedupon the need to dissipate the heat generated by the OCM reaction. Insome embodiments, multiple, tubular, fixed bed reactors can be arrangedin parallel to facilitate heat removal. At least a portion of the heatgenerated within the OCM reactor can be recovered, for example the heatcan be used to generate high temperature and/or pressure steam. Whereco-located with processes requiring a heat input, at least a portion ofthe heat generated within the OCM reactor may be transferred, forexample, using a heat transfer fluid, to the co-located processes. Whereno additional use exists for the heat generated within the OCM reactor,the heat can be released to the environment, for example, using acooling tower or similar evaporative cooling device. In someembodiments, an adiabatic fixed bed reactor system can be used and thesubsequent heat can be utilized directly to convert or crack alkanesinto olefins. In some embodiments, a fluidized bed reactor system can beutilized. OCM reactor systems useful in the context of the presentinvention may include those described in, for example, U.S. patentapplication Ser. No. 13/900,898 (filed May 23, 2013), which isincorporated herein by reference in its entirety for all purposes.

The methane feedstock for an OCM reactor can be provided from varioussources, such as non-OCM processes. In an example, methane is providedthrough natural gas, such as methane generated in a natural gas liquids(NGL) system.

Methane can be combined with a recycle stream from downstream separationunits prior to or during introduction into an OCM reactor. In the OCMreactor, methane can catalytically react with an oxidizing agent toyield C₂₊ compounds. The oxidizing agent can be oxygen (O₂), which maybe provided by way of air or enriched air. Oxygen can be extracted fromair, for example, in a cryogenic air separation unit.

To carry out an OCM reaction in conjunction with preferable catalyticsystems, the methane and oxygen containing gases generally need to bebrought up to appropriate reaction temperatures, e.g., typically inexcess of 450° C. for preferred catalytic OCM processes, before beingintroduced to the catalyst, in order to allow initiation of the OCMreaction. Once that reaction begins or “lights off,” then the heat ofthe reaction is typically sufficient to maintain the reactor temperatureat appropriate levels. Additionally, these processes may operate at apressure above atmospheric pressure, such as in the range of about 1 to30 bars (absolute).

In some cases, the oxidizing agent and/or methane are pre-conditionedprior to, or during, the OCM process. The reactant gases can bepre-conditioned prior to their introduction into a catalytic reactor orreactor bed, in a safe and efficient manner. Such pre-conditioning caninclude (i) mixing of reactant streams, such as a methane-containingstream and a stream of an oxidizing agent (e.g., oxygen) in an OCMreactor or prior to directing the streams to the OCM reactor, (ii)heating or pre-heating the methane-containing stream and/or the streamof the oxidizing agent using, for example, heat from the OCM reactor, or(iii) a combination of mixing and pre-heating. Such pre-conditioning canminimize, if not eliminate auto-ignition of methane and the oxidizingagent. Systems and methods for pre-conditioning reactant gases aredescribed in, for example, U.S. patent application Ser. No. 14/553,795,filed Nov. 25, 2014, which is entirely incorporated herein by reference.

A wide set of competitive reactions can occur simultaneously orsubstantially simultaneously with the OCM reaction, including totalcombustion of both methane and other partial oxidation products. An OCMprocess can yield C₂₊ compounds as well as non-C₂₊ impurities. The C₂₊compounds can include a variety of hydrocarbons, such as hydrocarbonswith saturated or unsaturated carbon-carbon bonds. Saturatedhydrocarbons can include alkanes, such as ethane, propane, butane,pentane and hexane. Unsaturated hydrocarbons may be more suitable foruse in downstream non-OCM processes, such as the manufacture ofpolymeric materials (e.g., polyethylene). Accordingly, it may bepreferable to convert at least some, all or substantially all of thealkanes in the C₂₊ compounds to compounds with unsaturated moieties,such as alkenes, alkynes, alkoxides, ketones, including aromaticvariants thereof.

Once formed, C₂₊ compounds can be subjected to further processing togenerate desired or otherwise predetermined chemicals. In somesituations, the alkane components of the C₂₊ compounds are subjected tocracking in an OCM reactor or a reactor downstream of the OCM reactor toyield other compounds, such as alkenes (or olefins). See, e.g., U.S.patent application Ser. No. 14/553,795, filed Nov. 25, 2014, which isentirely incorporated herein by reference.

In some situations, an OCM system generates ethylene that can besubjected to further processing to generate different hydrocarbons withthe aid of conversion processes (or systems). Such a process can be partof an ethylene to liquids (ETL) or ethylene, propene, butene gases toliquids. The ETL process includes OCM olefins gases, ethylene, propene,butene, or other OCM gaseous products to produce liquids. OCM-ETLprocess flow comprising one or more OCM reactors, separations units, andone or more conversion processes for generating higher molecular weighthydrocarbons. The conversion processes can be integrated in a switchableor selectable manner in which at least a portion or all of the ethylenecontaining product can be selectively directed to 1, 2, 3, 4, 5, 6, 7,8, 9, 10, or more different process paths to yield as many differenthydrocarbon products. An example OCM and ETL (collectively “OCM-ETL”herein) process is schematically illustrated in FIG. 1, which shows anOCM reactor system 100 that includes an OCM reactor train 102 coupled toan OCM product gas separation train 104. The OCM product gas separationtrain 104 can include various separation unit operations (“units”), suchas a distillation unit and/or a cryogenic separation unit. The ethylenerich effluent (shown as arrow 106) from the separation train 104 isrouted to multiple different ethylene conversion reactor systems andprocesses 110, e.g., ethylene conversion systems 110 a-110 e, which eachproduce different hydrocarbon products, e.g., products 120 a-120 e.Products 120 a-120 e can include, for example, hydrocarbons havingbetween three and twelve carbon atoms per molecule (C3-C12hydrocarbons).

Such hydrocarbons may be suitable for use as fuels for various machines,such as automobiles.

The fluid connection between the OCM reactor system 100 and each of thedifferent ethylene conversion systems 110 a-110 e can be controllableand selective, e.g., with the aid of a valve and control system, whichcan apportion the output of the OCM reactor system 100 to 1, 2, 3, 4, 5,6, 7, 8, 9, 10, or more different ethylene conversion systems. Theconversions systems 110 a-110 e can be ETL or gas to liquids (GTL)reactors. Valve and piping systems for accomplishing this may take avariety of different forms, including valves at each piping junction,multiport valves, multi-valve manifold assemblies, and the like. Otherdetails of the OCM-ETL process of FIG. 1 are provided in, for example,U.S. patent application Ser. No. 14/099,614, filed on Dec. 6, 2013,which is entirely incorporated herein by reference.

As noted, the present disclosure includes processes and systems forproduction of various higher hydrocarbons (i.e., C₃₊) from ethylene, andparticularly liquid hydrocarbon compositions. In some aspects, theethylene is itself derived from methane in a methane containingfeedstock, such as natural gas. Production of ethylene from methane canbe accomplished through a number of different catalytic pathways, forexample in some embodiments, the processes and systems of the disclosureconvert methane to ethylene through OCM in an OCM reactor system. Insome embodiments, the ethylene produced in the OCM reactor system ischarged to one or more ethylene conversion reactor systems where it canbe converted to a higher hydrocarbon, for example a different higherhydrocarbon in each of the ethylene conversion reactor systems.

OCM reactions, processes and systems can operate within economic andreasonable process windows. In some cases, catalysts, processes andreactor systems have been able to carry out OCM reactions attemperatures, pressures, selectivities and yields that are commerciallyattractive. See, e.g., U.S. patent application Ser. Nos. 13/115,082,13/479,767, 13/689,611, 13/739,954, 13/900,898, 13/901,319, 13/936,783,and 14/212,435, the full disclosures of which are incorporated herein byreference in their entirety for all purposes.

As used herein, an OCM process or system typically employs one or morereactor vessels that contain an appropriate OCM catalyst material,typically in conjunction with additional system components. A variety ofOCM catalysts have been described previously. See, e.g., U.S. Pat. Nos.5,712,217, 6,403,523, and 6,576,803, the full disclosures of which areincorporated herein by reference in their entirety for all purposes.Some catalysts have been developed that yield conversion and selectivitythat enable economic methane conversion under practical operatingconditions. These are described in, for example, Published U.S. PatentApplication No. 2012-0041246, as well as patent application Ser. No.13/479,767, filed May 24, 2012, and Ser. No. 13/689,611, filed Nov. 29,2012, the full disclosures of each of which are incorporated herein byreference in their entirety for all purposes.

Accordingly, in some embodiments, the disclosure provides a method ofproducing a hydrocarbon product, the method comprising: (a) introducingmethane and a source of oxidant into an OCM reactor system capable ofconverting methane to ethylene at reactor inlet temperatures of betweenabout 450° C. and 600° C. and reactor pressures of between about 15 psigand 125 psig, with C₂₊ selectivity of at least 50%, under conditions forthe conversion of methane to ethylene; (b) converting methane to aproduct gas comprising ethylene; (c) introducing at least a portion ofthe product gas into an integrated ethylene conversion reaction systems,the integrated ethylene conversion reaction system being configured forconverting ethylene into a higher hydrocarbon product; and (d)converting the ethylene into a higher hydrocarbon product.

In some embodiments, the method is for producing a plurality ofhydrocarbon products.

Accordingly, in some embodiments, the invention provides a method ofproducing a plurality of hydrocarbon products, the method comprising:(a) introducing methane and a source of oxidant into an OCM reactorsystem capable of converting methane to ethylene at reactor inlettemperatures of between about 450° C. and 600° C. and reactor pressuresof between about 15 psig and 125 psig, with C₂₊ selectivity of at least50%, under conditions for the conversion of methane to ethylene; (b)converting methane to a product gas comprising ethylene; (c) introducingseparate portions of the product gas into at least first and secondintegrated ethylene conversion reaction systems, each integratedethylene conversion reaction system being configured for convertingethylene into a different higher hydrocarbon product; and (d) convertingthe ethylene into different higher hydrocarbon products. In someembodiments, the integrated ethylene conversion systems are selectedfrom selective and full range ethylene conversion systems.

In some embodiments the methods further comprise introducing a portionof the product gas into at least a third integrated ethylene conversionsystem. Some embodiments further comprise introducing a portion of theproduct gas into at least first, second, third and fourth integratedethylene conversion systems.

In any of the methods described herein, the integrated ethyleneconversion systems can be selected from linear alpha olefin (LAO)systems, linear olefin systems, branched olefin systems, saturatedlinear hydrocarbon systems, branched hydrocarbon systems, saturatedcyclic hydrocarbon systems, olefinic cyclic hydrocarbon systems,aromatic hydrocarbon systems, oxygenated hydrocarbon systems,halogenated hydrocarbon systems, alkylated aromatic systems, andhydrocarbon polymer systems.

In some embodiments, the integrated ethylene conversion systems can beselected from LAO systems that produce one or more of 1-butene,1-hexene, 1-octene and 1-decene. For example, in certain embodiments atleast one of the LAO systems is configured for performing a selectiveLAO process.

In some embodiments, at least one of the integrated ethylene conversionsystems comprises a full range ethylene oligomerization systemconfigured for producing higher hydrocarbons in the range of C₄ to C₃₀.

In some embodiments, the OCM reactor system comprises nanowire OCMcatalyst material. In some embodiments, the product gas comprises lessthan 5 mol % of ethylene. For example, in certain embodiments, theproduct gas comprises less than 3 mol % of ethylene. In someembodiments, the product gas can further comprise one or more gasesselected from CO₂, CO, H₂, H₂O, C₂H₆, CH₄ and C₃₊ hydrocarbons.

In some embodiments, the method further comprises enriching the productgas for ethylene prior to introducing the separate portions of theproduct gas into the at least first and second integrated ethyleneconversion reaction systems.

In some embodiments, the method further comprises introducing aneffluent gas from the first or second integrated ethylene conversionreaction systems into the OCM reactor system. For example, in some ofthese embodiments the method further comprises converting methanepresent in the effluent gas to ethylene and charging the ethylene to oneor more of the integrated ethylene conversion systems.

In various embodiments, the disclosure is directed to a method ofproducing a plurality of hydrocarbon products, the method comprising:(a) introducing methane and a source of oxidant into an OCM reactorsystem capable of converting methane to ethylene at reactor inlettemperatures of between about 450° C. and 600° C. and reactor pressuresof between about 15 psig and 125 psig, with C₂₊ selectivity of at least50%, under conditions for the conversion of methane to ethylene; (b)recovering ethylene from the OCM reactor system; and (c) introducingseparate portions of the ethylene recovered from the OCM reactor systeminto at least two integrated, but discrete and different catalyticethylene conversion reaction systems for converting ethylene into atleast two different higher hydrocarbon products.

In some embodiments, the at least two ethylene conversion systems areselected from selective and full range ethylene conversion systems. Insome embodiments, the at least two ethylene conversion systems compriseat least three ethylene conversion systems. For example, in someembodiments the at least two ethylene conversion systems comprise atleast four ethylene conversion systems.

In yet more embodiments, the at least two ethylene conversion systemsare selected from linear alpha olefin (LAO) systems, linear olefinsystems, branched olefin systems, saturated linear hydrocarbon systems,branched hydrocarbon systems, saturated cyclic hydrocarbon systems,olefinic cyclic hydrocarbon systems, aromatic hydrocarbon systems,oxygenated hydrocarbon systems, halogenated hydrocarbon systems,alkylated aromatic systems, and hydrocarbon polymer systems.

In some cases, the at least two ethylene conversion systems are selectedfrom LAO systems that produce one or more of 1-butene, 1-hexene,1-octene and 1-decene. For example, in some embodiments at least one ofthe at least two LAO processes comprises a selective LAO process, and inother exemplary embodiments at least one of the at least two ethyleneconversion systems comprises a full range ethylene oligomerizationsystem for producing higher hydrocarbons in the range of C₄ to C₃₀. Insome instances, the OCM reactor system comprises nanowire OCM catalystmaterial.

In some embodiments, the disclosure provides a method of producing aplurality of liquid hydrocarbon products, comprising: (a) convertingmethane to a product gas comprising ethylene using a catalytic reactorprocess; and (b) contacting separate portions of the product gas with atleast two discrete catalytic reaction systems selected from linear alphaolefin (LAO) systems, linear olefin systems, branched olefin systems,saturated linear hydrocarbon systems, branched hydrocarbon systems,saturated cyclic hydrocarbon systems, olefinic cyclic hydrocarbonsystems, aromatic hydrocarbon systems, oxygenated hydrocarbon systems,halogenated hydrocarbon systems, alkylated aromatic systems, andhydrocarbon polymer systems.

In some cases, a method of producing a plurality of liquid hydrocarbonproducts is provided. The method comprises: (a) converting methane toethylene using a catalytic reactor process; (b) recovering ethylene fromthe catalytic reactor process; and (c) contacting separate portions ofthe ethylene recovered from the OCM reactor system with at least twodiscrete catalytic reaction systems selected from linear alpha olefin(LAO) systems, linear olefin systems, branched olefin systems, saturatedlinear hydrocarbon systems, branched hydrocarbon systems, saturatedcyclic hydrocarbon systems, olefinic cyclic hydrocarbon systems,aromatic hydrocarbon systems, oxygenated hydrocarbon systems,halogenated hydrocarbon systems, alkylated aromatic systems, andhydrocarbon polymer systems.

Some embodiments of the present disclosure are directed to a processingsystem for preparation of C₂₊ hydrocarbon products from methane. Forexample, in some embodiments the invention provides a processing systemcomprising: (a) an OCM reactor system comprising an OCM catalyst, theOCM reactor system being fluidly connected at an input, to a source ofmethane and a source of oxidant; (b) an integrated ethylene conversionreactor system, the ethylene reactor system being configured to convertethylene to a higher hydrocarbon; and (c) a selective coupling betweenthe OCM reactor system and the ethylene reactor system, the selectivecoupling configured to selectively direct a portion or all of theproduct gas to the ethylene conversion reactor system.

In some instances, the disclosure provides a processing systemcomprising: (a) an OCM reactor system comprising an OCM catalyst, theOCM reactor system being fluidly connected at an input, to a source ofmethane and a source of oxidant; (b) at least first and second catalyticethylene conversion reactor systems, the first catalytic ethylenereactor system being configured to convert ethylene to a first higherhydrocarbon, and the second catalytic ethylene reactor system beingconfigured to convert ethylene to a second higher hydrocarbon differentfrom the first higher hydrocarbon; and (c) a selective coupling betweenthe OCM reactor system and the first and second catalytic ethylenereactor systems configured to selectively direct a portion or all of theproduct gas to each of the first and second catalytic ethylene reactorsystems.

In some embodiments, the ethylene conversion systems are selected fromlinear alpha olefin (LAO) systems, linear olefin systems, branchedolefin systems, saturated linear hydrocarbon systems, branchedhydrocarbon systems, saturated cyclic hydrocarbon systems, olefiniccyclic hydrocarbon systems, aromatic hydrocarbon systems, oxygenatedhydrocarbon systems, halogenated hydrocarbon systems, alkylated aromaticsystems, ethylene copolymerization systems, and hydrocarbon polymersystems.

In some instances, the OCM catalyst comprises a nanowire catalyst. Insome embodiments, the system further comprises an ethylene recoverysystem fluidly coupled between the OCM reactor system and the at leastfirst and second catalytic ethylene conversion reactor systems, theethylene recovery system configured for enriching the product gas forethylene.

In some cases, the disclosure is directed to a processing system, theprocessing system comprising: (a) an OCM reactor system comprising anOCM catalyst, the OCM reactor system being fluidly connected at aninput, to a source of methane and a source of oxidant; (b) an ethylenerecovery system fluidly coupled to the OCM reactor system at an outlet,for recovering ethylene from an OCM product gas; (c) at least first andsecond catalytic ethylene conversion reactor systems, the firstcatalytic ethylene reactor system being configured to convert ethyleneto a first higher hydrocarbon composition, and the second catalyticethylene reactor system being configured to convert ethylene to a secondhigher hydrocarbon composition different from the first higherhydrocarbon composition; and (d) a selective coupling between the outletof the ethylene recovery system and the first and second catalyticethylene reactor systems to selectively direct a portion or all of theethylene recovered from the OCM product gas to each of the first andsecond catalytic ethylene reactor systems.

In some cases, two or more of the at least two ethylene conversionsystems are selected from linear alpha olefin (LAO) systems, linearolefin systems, branched olefin systems, saturated linear hydrocarbonsystems, branched hydrocarbon systems, saturated cyclic hydrocarbonsystems, olefinic cyclic hydrocarbon systems, aromatic hydrocarbonsystems, oxygenated hydrocarbon systems, halogenated hydrocarbonsystems, alkylated aromatic systems, ethylene copolymerization systems,and hydrocarbon polymer systems. In other embodiments, the OCM catalystcomprises a nanowire catalyst.

In some embodiments, the catalyst systems used in any of the abovedescribed OCM reaction comprise nanowire catalysts. Such nanowirecatalysts can include substantially straight nanowires or nanowireshaving a curved, twisted or bent morphology. The actual lengths of thenanowire catalysts may vary. For example in some embodiments, thenanowires have an actual length of between 100 nm and 100 μm. In otherembodiments, the nanowires have an actual length of between 100 nm and10 μm. In other embodiments, the nanowires have an actual length ofbetween 200 nm and 10 μm. In other embodiments, the nanowires have anactual length of between 500 nm and 5 μm. In other embodiments, theactual length is greater than 5 μm. In other embodiments, the nanowireshave an actual length of between 800 nm and 1000 nm. In other furtherembodiments, the nanowires have an actual length of 900 nm. As notedbelow, the actual length of the nanowires may be determined by TEM, forexample, in bright field mode at 5 keV.

The diameter of the nanowires may be different at different points alongthe nanowire backbone. However, the nanowires comprise a mode diameter(i.e., the most frequently occurring diameter). As used herein, thediameter of a nanowire refers to the mode diameter. In some embodiments,the nanowires have a diameter of between 1 nm and 10 μm, between 1 nmand 1 μm, between 1 nm and 500 nm, between 1 nm and 100 nm, between 7 nmand 100 nm, between 7 nm and 50 nm, between 7 nm and 25 nm, or between 7nm and 15 nm. On other embodiments, the diameter is greater than 500 nm.As noted below, the diameter of the nanowires may be determined by TEM,for example, in bright field mode at 5 keV.

The nanowire catalysts may have different aspect ratios. In someembodiments, the nanowires have an aspect ratio of greater than 10:1. Inother embodiments, the nanowires have an aspect ratio greater than 20:1.In other embodiments, the nanowires have an aspect ratio greater than50:1. In other embodiments, the nanowires have an aspect ratio greaterthan 100:1.

In some embodiments, the nanowires comprise a solid core while in otherembodiments, the nanowires comprise a hollow core. In general, themorphology of a nanowire (including length, diameter, and otherparameters) can be determined by transmission electron microscopy (TEM).Transmission electron microscopy (TEM) is a technique whereby a beam ofelectrons is transmitted through an ultra-thin specimen, interactingwith the specimen as it passes through. An image is formed from theinteraction of the electrons transmitted through the specimen. The imageis magnified and focused onto an imaging device, such as a fluorescentscreen, on a layer of photographic film or detected by a sensor such asa CCD camera.

In some embodiments, the nanowire catalysts comprise one or multiplecrystal domains, e.g., monocrystalline or polycrystalline, respectively.In some other embodiments, the average crystal domain of the nanowiresis less than 100 nm, less than 50 nm, less than 30 nm, less than 20 nm,less than 10 nm, less than 5 nm, or less than 2 nm. Crystal structure,composition, and phase, including the crystal domain size of thenanowires, can be determined by XRD.

Typically, the nanowire catalytic material comprises a plurality ofnanowires. In certain embodiments, the plurality of nanowires form amesh of randomly distributed and, to various degrees, interconnectednanowires, that presents a porous matrix.

The total surface area per gram of a nanowire or plurality of nanowiresmay have an effect on the catalytic performance. Pore size distributionmay affect the nanowires catalytic performance as well. Surface area andpore size distribution of the nanowires or plurality of nanowires can bedetermined by BET (Brunauer, Emmett, Teller) measurements. BETtechniques utilize nitrogen adsorption at various temperatures andpartial pressures to determine the surface area and pore sizes ofcatalysts. There are BET techniques for determining surface area andpore size distribution currently available. In some embodiments thenanowires have a surface area of between 0.0001 and 3000 m²/g, between0.0001 and 2000 m²/g, between 0.0001 and 1000 m²/g, between 0.0001 and500 m²/g, between 0.0001 and 100 m²/g, between 0.0001 and 50 m²/g,between 0.0001 and 20 m²/g, between 0.0001 and 10 m²/g or between 0.0001and 5 m²/g. In some embodiments the nanowires have a surface area ofbetween 0.001 and 3000 m²/g, between 0.001 and 2000 m²/g, between 0.001and 1000 m²/g, between 0.001 and 500 m²/g, between 0.001 and 100 m²/g,between 0.001 and 50 m²/g, between 0.001 and 20 m²/g, between 0.001 and10 m²/g or between 0.001 and 5 m²/g. In some other embodiments thenanowires have a surface area of between 2000 and 3000 m²/g, between1000 and 2000 m²/g, between 500 and 1000 m²/g, between 100 and 500 m²/g,between 10 and 100 m²/g, between 5 and 50 m²/g, between 2 and 20 m²/g orbetween 0.0001 and 10 m²/g. In other embodiments, the nanowires have asurface area of greater than about 2000 m²/g, greater than about 1000m²/g, greater than about 500 m²/g, greater than about 100 m²/g, greaterthan about 50 m²/g, greater than about 20 m²/g, greater than about 10m²/g, greater than about 5 m²/g, greater than about 1 m²/g, greater thanabout 0.0001 m²/g.

The nanowire catalysts and catalyst compositions used in conjunctionwith the processes and systems of some embodiments of the invention mayhave any number of compositions and/or morphologies. These nanowirecatalysts may be inorganic and either polycrystalline ormono-crystalline. In some other embodiments, the nanowires are inorganicand polycrystalline. In certain examples, the nanowire catalystscomprise one or more elements from any of Groups 1 through 7,lanthanides, actinides or combinations thereof. Thus in certain aspects,the catalysts comprise an inorganic catalytic polycrystalline nanowire,the nanowire having a ratio of effective length to actual length of lessthan one and an aspect ratio of greater than ten as measured by TEM inbright field mode at 5 keV, wherein the nanowire comprises one or moreelements from any of Groups 1 through 7, lanthanides, actinides orcombinations thereof.

In still other cases, the nanowire catalysts comprise one or more metalelements from any of Groups 1-7, lanthanides, actinides or combinationsthereof, for example, the nanowires may be mono-metallic, bi-metallic,tri-metallic, etc. (i.e., contain one, two, three, etc. metal elements),where the metal elements may be present in the nanowires in elemental oroxidized form, or in the form of a compound comprising a metal element.The metal element or compound comprising the metal element may be in theform of oxides, hydroxides, oxyhydroxides, salts, hydrated oxides,carbonates, oxy-carbonates, sulfates, phosphates, acetates, oxalates andthe like. The metal element or compound comprising the metal element mayalso be in the form of any of a number of different polymorphs orcrystal structures.

In some examples, metal oxides may be hygroscopic and may change formsonce exposed to air, may absorb carbon dioxide, may be subjected toincomplete calcination or any combination thereof. Accordingly, althoughthe nanowires are often referred to as metal oxides, in some embodimentsthe nanowires also comprise hydrated oxides, oxyhydroxides, hydroxides,oxycarbonates (or oxide carbonates), carbonates or combinations thereof.

In some cases, the nanowires comprise one or more metal elements fromGroup 1, Group 2, Group 3, Group 4, Group 5, Group 6, Group 7,lanthanides, and/or actinides, or combinations of these, as well asoxides of these metals. In other cases, the nanowires comprisehydroxides, sulfates, carbonates, oxide carbonates, acetates, oxalates,phosphates (including hydrogen phosphates and dihydrogenphosphates),oxy-carbonates, oxyhalides, hydroxyhalides, oxyhydroxides, oxysulfates,mixed oxides or combinations thereof of one or more metal elements fromany of Groups 1-7, lanthanides, actinides or combinations thereof.Examples of such nanowire materials include, but are not limited tonanowires comprising, e.g., Li₂CO₃, LiOH, Li₂O, Li₂C₂O₄, Li₂SO₄, Na₂CO₃,NaOH, Na₂O, Na₂C₂O₄, Na₂SO₄, K₂CO₃, KOH, K₂O, K₂C₂O₄, K₂SO₄, Cs₂CO₃,CsOH, Cs₂O, CsC₂O₄, CsSO₄, Be(OH)₂, BeCO₃, BeO, BeC₂O₄. BeSO₄, Mg(OH)₂,MgCO₃, MgO, MgC₂O₄. MgSO₄, Ca(OH)₂, CaO, CaCO₃, CaC₂O₄, CaSO₄, Y₂O₃,Y₂(CO₃)₃, Y(OH)₃, Y₂(C₂O₄)₃, Y₂(SO₄)₃, Zr(OH)₄, ZrO(OH)₂, ZrO2,Zr(C₂O₄)₂, Zr(SO₄)₂, Ti(OH)₄, TiO(OH)₂, TiO₂, Ti(C₂O₄)₂, Ti(SO₄)₂, BaO,Ba(OH)₂, BaCO₃, BaC₂O₄, BaSO₄, La(OH)₃, La₂O₃, La₂(C₂O₄)₃, La₂(SO₄)₃,La₂(CO₃)₃, Ce(OH)₄, CeO₂, Ce₂O₃, Ce(C₂O₄)₂, Ce(SO₄)₂, Ce(CO₃)₂, ThO₂,Th(OH)₄, Th(C₂O₄)₂, Th(SO₄)₂, Th(CO₃)₂, Sr(OH)₂, SrCO₃, SrO, SrC₂O₄,SrSO₄, Sm₂O₃, Sm(OH)₃, Sm₂(CO₃)₃, Sm₂(C₂O₄)₃, Sm₂(SO₄)₃, LiCa₂Bi₃O₄Cl₆,NaMnO₄, Na₂WO₄, NaMn/WO₄, CoWO₄, CuWO₄, K/SrCoO₃, K/Na/SrCoO₃,Na/SrCoO₃, Li/SrCoO₃, SrCoO₃, Mg₆MnO₈, LiMn₂O₄, Li/Mg₆MnO₈,Na₁₀Mn/W₅O₁₇, Mg₃Mn₃B₂O₁₀, Mg₃(BO₃)₂, molybdenum oxides, molybdenumhydroxides, molybdenum oxalates, molybdenum sulfates, Mn₂O₃, Mn₃O₄,manganese oxides, manganese hydroxides, manganese oxalates, manganesesulfates, manganese tungstates, manganese carbonates, vanadium oxides,vanadium hydroxides, vanadium oxalates, vanadium sulfates, tungstenoxides, tungsten hydroxides, tungsten oxalates, tungsten sulfates,neodymium oxides, neodymium hydroxides, neodymium carbonates, neodymiumoxalates, neodymium sulfates, europium oxides, europium hydroxides,europium carbonates, europium oxalates, europium sulfates, praseodymiumoxides, praseodymium hydroxides, praseodymium carbonates, praseodymiumoxalates, praseodymium sulfates, rhenium oxides, rhenium hydroxides,rhenium oxalates, rhenium sulfates, chromium oxides, chromiumhydroxides, chromium oxalates, chromium sulfates, potassium molybdenumoxides/silicon oxide or combinations thereof.

Still other examples of these nanowire materials include, but are notlimited to, nanowires comprising, e.g., Li₂O, Na₂O, K₂O, Cs₂O, BeO MgO,CaO, ZrO(OH)₂, ZrO₂, TiO₂, TiO(OH)₂, BaO, Y₂O₃, La₂O₃, CeO₂, Ce₂O₃,ThO₂, SrO, Sm₂O₃, Nd₂O₃, Eu₂O₃, Pr₂O₃, LiCa₂Bi₃O₄C₁₆, NaMnO₄, Na₂WO₄,Na/Mn/WO₄, Na/MnWO₄, Mn/WO₄, K/SrCoO₃, K/Na/SrCoO₃, K/SrCoO₃, Na/SrCoO₃,Li/SrCoO₃, SrCoO₃, Mg₆MnO₈, Na/B/Mg₆MnO₈, Li/B/Mg₆MnO₈, Zr₂Mo₂O₈,molybdenum oxides, Mn₂O₃, Mn₃O₄, manganese oxides, vanadium oxides,tungsten oxides, neodymium oxides, rhenium oxides, chromium oxides, orcombinations thereof. A variety of different nanowire compositions havebeen described in, e.g., Published U.S. Patent Application No.2012-0041246 and U.S. patent application Ser. No. 13/689,611, filed Nov.29, 2012 (the full disclosures of which are incorporated herein in theirentirety for all purposes), and are envisioned for use in conjunctionwith the present invention.

Products produced from these catalytic reactions typically include CO,CO₂, H₂O, C₂₊ hydrocarbons, such as ethylene, ethane, and larger alkanesand alkenes, such as propane and propylene. In some embodiments, the OCMreactor systems operate to convert methane into desired higherhydrocarbon products (ethane, ethylene, propane, propylene, butanes,pentanes, etc.), collectively referred to as C₂₊ compounds, with highyield. In particular, the progress of the OCM reaction is generallydiscussed in terms of methane conversion, C₂₊ selectivity, and C₂₊yield. As used herein, methane conversion generally refers to thepercentage or fraction of methane introduced into the reaction that isconverted to a product other than methane. C₂₊ selectivity generallyrefers to the percentage of all non-methane, carbon containing productsof the OCM reaction that are the desired C₂₊ products, e.g., ethane,ethylene, propane, propylene, etc. Although primarily stated as C₂₊selectivity, it will be appreciated that selectivity may be stated interms of any of the desired products, e.g., just C2, or just C2 and C3.Finally, C₂₊ yield generally refers to the amount of carbon that isincorporated into a C₂₊ product as a percentage of the amount of carbonintroduced into a reactor in the form of methane. This may generally becalculated as the product of the conversion and the selectivity dividedby the number of carbon atoms in the desired product. C₂₊ yield istypically additive of the yield of the different C₂₊ components includedin the C₂₊ components identified, e.g., ethane yield+ethyleneyield+propane yield+propylene yield etc.).

Exemplary OCM processes and systems typically provide a methaneconversion of at least 10% per process pass in a single integratedreactor system (e.g., single isothermal reactor system or integratedmultistage adiabatic reactor system), with a C₂₊ selectivity of at least50%, but at reactor inlet temperatures of between 400 and 600° C. and atreactor inlet pressures of between about 15 psig and about 150 psig.Thus, the catalysts employed within these reactor systems are capable ofproviding the described conversion and selectivity under the describedreactor conditions of temperature and pressure. In the context of someOCM catalysts and system embodiments, it will be appreciated that thereactor inlet or feed temperatures typically substantially correspond tothe minimum “light-off” or reaction initiation temperature for thecatalyst or system. Restated, the feed gases are contacted with thecatalyst at a temperature at which the OCM reaction is able to beinitiated upon introduction to the reactor. Because the OCM reaction isexothermic, once light-off is achieved, the heat of the reaction can beexpected to maintain the reaction at suitable catalytic temperatures,and even generate excess heat.

In some aspects, the OCM reactors and reactor systems, when carrying outthe OCM reaction, operate at pressures of between about 15 psig andabout 125 psig at the above described temperatures, while providing theconversion and selectivity described herein, and in even moreembodiments, at pressures less than 100 psig, e.g., between about 15psig and about 100 psig.

Examples of particularly useful catalyst materials are described in, forexample, Published U.S. Patent Application No. 2012-0041246, as well aspatent application Ser. No. 13/479,767, filed May 24, 2012, and Ser. No.13/689,611, filed Nov. 29, 2012, which are incorporated herein byreference in their entirety for all purposes. In some embodiments, thecatalysts comprise bulk catalyst materials, e.g., having relativelyundefined morphology or, in certain embodiments, the catalyst materialcomprises, at least in part, nanowire containing catalytic materials. Ineither form, the catalysts used in accordance with the present inventionmay be employed under the full range of reaction conditions describedabove, or in any narrower described range of conditions. Similarly, thecatalyst materials may be provided in a range of different larger scaleforms and formulations, e.g., as mixtures of materials having differentcatalytic activities, mixtures of catalysts and relatively inert ordiluent materials, incorporated into extrudates, pellets, or monolithicforms, or the like. Ranges of exemplary catalyst forms and formulationsare described in, for example, U.S. patent application Ser. No.13/901,319 and U.S. Provisional Patent Application No. 62/051,779, thefull disclosures of which are incorporated herein by reference in theirentireties for all purposes.

The reactor vessels used for carrying out the OCM reaction in the OCMreactor systems of the invention may include one or more discretereactor vessels each containing OCM catalyst material, fluidly coupledto a methane source and a source of oxidant as further discussedelsewhere herein. Feed gas containing methane (e.g., natural gas) iscontacted with the catalyst material under conditions suitable forinitiation and progression of the reaction within the reactor tocatalyze the conversion of methane to ethylene and other products.

For example, in some embodiments the OCM reactor system comprises one ormore staged reactor vessels operating under isothermal or adiabaticconditions, for carrying out OCM reactions. For adiabatic reactorsystems, the reactor systems may include one, two, three, four, five ormore staged reactor vessels arranged in series, which are fluidlyconnected such that the effluent or “product gas” of one reactor isdirected, at least in part, to the inlet of a subsequent reactor. Suchstaged serial reactors provide higher yield for the overall process, byallowing catalytic conversion of previously unreacted methane. Theseadiabatic reactors are generally characterized by the lack of anintegrated thermal control system used to maintain little or notemperature gradient across the reactor. With no integrated temperaturecontrol system, the exothermic nature of the OCM reaction results in atemperature gradient across the reactor indicative of the progress ofthe reaction, where the inlet temperature can range from about 450° C.to about 600° C., while the outlet temperature ranges from about 700° C.to about 900° C. Typically, such temperature gradients can range fromabout 100° C. to about 450° C. By staging adiabatic reactors, withinterstage cooling systems, one can step through a more completecatalytic reaction without generating extreme temperatures, e.g., inexcess of 900° C.

In operation of certain embodiments, methane-containing feed gas isintroduced into the inlet side of a reactor vessel, e.g., the firstreactor in a staged reactor system. Within this reactor, the methane isconverted into C₂₊ hydrocarbons, as well as other products, as discussedabove. At least a portion of the product gas stream is then cooled to anappropriate temperature and introduced into a subsequent reactor stagefor continuation of the catalytic reaction. In particular, the effluentfrom a preceding reactor, which in some cases may include unreactedmethane, can provide at least a portion of the methane source for asubsequent reactor. An oxidant source and a methane source, separatefrom the unreacted methane from the first reactor stage, are alsotypically coupled to the inlet of each subsequent reactor.

In some aspects, the reactor systems include one or more ‘isothermal’reactors, that maintain a relatively low temperature gradient across theoverall reactor bed, e.g., between the inlet gas and outlet or productgas, through the inclusion of integrated temperature control elements,such as coolant systems that contact heat exchange surfaces on thereactor to remove excess heat, and maintain a flat or insignificanttemperature gradient between the inlet and outlet of the reactor.Typically, such reactors utilize molten salt or other coolant systemsthat operate at temperatures below 593° C. As with adiabatic systems,isothermal reactor systems may include one, two, three or more reactorsthat may be configured in serial or parallel orientation. Reactorsystems for carrying out these catalytic reactions are also described inU.S. patent application Ser. No. 13/900,898, the full disclosure ofwhich is incorporated herein by reference in its entirety for allpurposes.

The OCM reactor systems used in certain embodiments of the presentinvention also typically include thermal control systems that areconfigured to maintain a desired thermal or temperature profile acrossthe overall reactor system, or individual reactor vessels. In thecontext of adiabatic reactor systems, it will be appreciated that thethermal control systems include, for example, heat exchangers disposedupstream, downstream or between serial reactors within the overallsystem in order to maintain the desired temperature profile across theone or more reactors. In the context of reactors carrying out exothermicreactions, like OCM, such thermal control systems also optionallyinclude control systems for modulating flow of reactants, e.g., methanecontaining feed gases and oxidant, into the reactor vessels in responseto temperature information feedback, in order to modulate the reactionsto achieve the thermal profiles of the reactors within the desiredtemperature ranges. These systems are also described in U.S. patentapplication Ser. No. 13/900,898, previously incorporated herein byreference.

For isothermal reactors, such thermal control systems include theforegoing, as well as integrated heat exchange components, such asintegrated heat exchangers built into the reactors, such as tube/shellreactor/heat exchangers, where a void space is provided surrounding areactor vessel or through which one or more reactor vessels or tubespass. A heat exchange medium is then passed through the void to removeheat from the individual reactor tubes. The heat exchange medium is thenrouted to an external heat exchanger to cool the medium prior torecirculation into the reactor.

Following the OCM process, ethylene optionally may be recovered from theOCM product gas using an ethylene recovery process that separatesethylene present in the product gas from other components, such asresidual, i.e., unreacted methane, ethane, and higher hydrocarbons, suchas propane, butanes, pentanes and the like. Alternatively, the OCMproduct gas is used in subsequent reactions, as described below, withoutfurther purification or separation of the ethylene. In various otherembodiments, the OCM product gas is enriched for ethylene before beingused in subsequent reactions. In this respect, “enriched” includes, butis not limited to, operations which increases the overall mol % ofethylene in the product gas.

In accordance with the present disclosure, ethylene derived frommethane, e.g., using the OCM processes and systems, is further processedinto higher hydrocarbon compositions, and particularly liquidhydrocarbon compositions. For ease of discussion, reference to OCMprocesses and systems, when referring to their inclusion in an overallprocess flow, from methane to higher hydrocarbon compositions, alsooptionally includes intermediate process steps involved in purificationof ethylene from an OCM product gas, e.g., recycling of product gasesthrough the OCM reactor system, separations of methane and higherhydrocarbons, e.g., NGLs and other C₂₊ compounds, from the OCM productgas, and the like. Examples of such intermediate processes include, forexample, cryogenic or lean oil separation systems, temperature swingadsorption (TSA), pressure swing adsorption (PSA), and membraneseparations, for separation of different hydrocarbon and othercomponents from ethylene, e.g., CO, CO₂, water, nitrogen, residualmethane, ethane, propane, and other higher hydrocarbon compounds,potentially present in the OCM product gas. Examples of such systems aredescribed in, e.g., U.S. patent application Ser. Nos. 13/739,954,13/936,783, and 13/936,870, the full disclosures of which areincorporated herein by reference in their entirety for all purposes.

FIG. 10 schematically illustrates an exemplary OCM system withintegrated separations system component or components. In particular,shown in FIG. 10 is an exemplary process flow diagram depicting aprocess 1000 for methane based C₂ production, in a product gas from anOCM reactor or reactors 1002, and separation process 1004, that includesa first separator 1006 providing the C₂-rich effluent 1052 and amethane/nitrogen-rich effluent 1074. In the embodiment illustrated inFIG. 10, the OCM product gas from the OCM reactor(s) 1002 is compressedthrough compressor 1026. The temperature of the compressed OCM productgas 1050 is reduced using one or more heat exchangers 1010. Thetemperature of the compressed OCM product gas 1050 may be reducedthrough the use of an external provided cooling media, introduction ofor thermal exchange with a cool process stream, or combinations ofthese. Reducing the temperature of the OCM product gas 1050 willtypically condense at least a portion of the higher boiling pointcomponents in the compressed OCM product gas 1050, including at least aportion of the C₂ and heavier hydrocarbon components present in thecompressed OCM product gas 1050.

At least a portion of the condensed high boiling point components can beseparated from the compressed OCM product gas 1050 using one or moreliquid gas separators, such as knockout drums 1012 to provide an OCMproduct gas condensate 1054 and a compressed OCM product gas 1056. TheOCM product gas condensate 1054 is introduced to the first separator1006 and at least a portion 1058 of the compressed OCM product gas 1056can be introduced to one or more turboexpanders 1014. The isentropicexpansion of the compressed OCM product gas 1058 within theturboexpanders 1014 can produce shaft work useful for driving one ormore compressors or other devices in the separation unit 1004. Theisentropic expansion of the compressed OCM product gas 1058 with theturboexpanders reduces the temperature of the compressed OCM product gas1060 that exits from the one or more turboexpanders. The compressed OCMproduct gas 1060 from the one or more turboexpanders 1014 is introducedto the first separator 1006.

The first separator 1006 can be any system, device or combination ofsystems and devices suitable for promoting the separation of C₂ andheavier hydrocarbons from a gas stream that includes methane andnitrogen. For example, cryogenic distillation at a relatively hightemperature may be used to promote separation of the C₂ and heavierhydrocarbons from the methane and nitrogen components in the gas stream.The C₂-rich effluent 1052 is withdrawn from the first separator 1006 anda mixed nitrogen and methane containing gas mixture 1074 is alsowithdrawn from the first separator 1054. The nitrogen content of thenitrogen/methane containing gas mixture 1074 withdrawn from the firstseparator 1006 can be about 95 mol % or less; about 85 mol % or less;about 75 mol % or less; about 55 mol % or less; about 30 mol % or less.The balance of the nitrogen/methane gas mixture 1054 comprisesprincipally methane with small quantities of hydrogen, carbon monoxide,and inert gases such as argon. The nitrogen/methane rich gas 1074 isthen further cooled using heat exchanger(s) 1022, and the coolednitrogen/methane containing gas 1076 is then introduced into secondseparator 1008, described in more detail, below.

In at least some embodiments, the first separator functions as a“demethanizer” based upon its ability to separate methane from the C₂and heavier hydrocarbon components. An exemplary first separator 1006includes a vertical distillation column operating at below ambienttemperature and above ambient pressure. In particular, the operatingtemperature and pressure within the first separator 1006 can beestablished to improve the recovery of the desired C₂ hydrocarbons inthe C₂-rich effluent 1052. In exemplary embodiments, the first separator1006 can have an overhead operating temperature of from about −260° F.(−162° C.) to about −180° F. (−118° C.); about −250° F. (−157° C.) toabout −190° F. (−123° C.); about −240° F. (−151° C.) to about −200° F.(−129° C.; or even from about −235° F. (−148° C.) to about −210° F.(−134° C.) and a bottom operating temperature of from about −150° F.(−101° C.) to about −50° F. (−46° C.); about −135° F. (−93° C.) to about−60° F. (−51° C.); from about −115° F. (−82° C.) to about −70° F. (−57°C.); or about −100° F. (−73° C.) to about −80° F. (−62° C.). In anexemplary aspect, the first separator 1006 may operate at pressures offrom about 30 psig (205 kPa) to about 130 psig (900 kPa); about 40 psig(275 kPa) to about 115 psig (790 kPa); about 50 psig (345 kPa) to about95 psig (655 kPa); or about 60 psig (415 kPa) to about 80 psig (550kPa).

The temperature of at least a portion of the C₂-rich effluent 1052 fromthe first separator 1006 can be increased in one or more heat exchangers1016, again using an externally supplied heat transfer medium,introduction of, or thermal contact, with a warmer process flow stream,or a combination of these, or other heating systems. The one or moreheat exchanger devices 1016 may include any type of heat exchange deviceor system, including but not limited to one or more plate and frame,shell and tube or similar heat exchanger system. After exiting the oneor more heat exchangers 1016, the heated C₂-rich effluent 1052 may be attemperatures of 50° F. (10° C.) or less; 25° F. (−4° C.) or less; about0° F. (−18° C.) or less; about −25° F. (−32° C.) or less; or about −50°F. (−46° C.) or less. Furthermore, the pressure may be about 130 psig(900 kPa) or less; about 115 psig (790 kPa or less; about 100 psig (690kPa) or less; or about 80 psig (550 kPa) or less.

In some embodiments, a portion 1062 of the OCM product gas 1056 removedfrom the knockout drum 1012 and not introduced into the one or moreturboexpanders 1014 can be cooled using one or more heat exchangers1018. As noted previously, the heat exchangers may include any type ofheat exchanger suitable for the operation. The temperature of theportion 1062 of the OCM product gas 1056 can be decreased using one ormore refrigerants, one or more relatively cool process flows, orcombinations of these. The cooled portion 1064 of the OCM product gas1056 containing a mixture of nitrogen and methane is introduced into thesecond separator 1008.

The second separator 1008 may include any system, device or combinationof systems and devices suitable for separating methane from nitrogen.For example, cryogenic distillation at a relatively low temperature canbe used to promote the separation of liquid methane from gaseousnitrogen within the second separator 1008. An exemplary second separator1008 may include another vertical distillation column operatingsignificantly below ambient temperature and above ambient pressure, andalso generally below the temperature of a cryogenic distillation columnoperating as the first separator, e.g., as described above. For example,the second separator 1008 may have an overhead operating temperature offrom about −340° F. (−210° C.) to about −240° F. (−151° C.); from about−330° F. (−201° C.) to about −250° F. (−157° C.); about −320° F. (−196°C.) to about −260° F. (−162° C.); about −310° F. (−190° C.) to about−270° F. (−168° C.); or about 300° F. (−184° C.) to about −280° F.(−173° C.); and a bottom operating temperature of from about −280° F.(−173° C.) to about −170° F. (112° C.); about −270° F. (−168° C.) toabout −180° F. (−118° C.); about −260° F. (−162° C.) to about −190° F.(−123° C.); about −250° F. (−159° C.) to about −200° F. (−129° C.); orabout −240° F. (−151° C. to about −210° F. (−134° C.). In exemplaryembodiments, the second separator 1008 will typically operate atpressures of from about 85 psig (585 kPa) or less; about 70 psig (480kPa) or less; about 55 psig (380 kPa) or less; or about 40 psig (275kPa) or less.

The temperature of at least a portion of the methane-rich effluent 1066from the second separator 1008 can be increased using one or more heatexchangers 1020, as described above. After exiting the one or more heatexchangers 1020, in exemplary embodiments the temperature of themethane-rich effluent 1066 may be about 125° F. (52° C.) or less; about100° F. (38° C.) or less; or about 90° F. (32° C.) or less, while thepressure of the effluent 1066 may be about 150 psig (1035 kPa) or less;about 100 psig (690 kPa) or less, or about 50 psig (345 kPa) or less. Inan embodiment, e.g., schematically illustrated in FIG. 10, at least aportion of the methane-rich effluent 1066 may be recycled back into thefeedstock gas 1068 for the OCM reactor(s) 1002, the feedstock gas/oxygenmixture 1070 the compressed oxygen containing gas 1072 (from compressor1028) or directly to the one or more OCM reactors 1002.

The temperature of at least a portion of the nitrogen-rich effluent 1068from second separator 1008 can be increased using one or more heatexchangers 1024 like those described above, such that the temperaturemay be raised to about 125° F. (52° C.) or less; 100° F. (38° C.) orless; or about 90° F. (32° C.) or less, with a pressure of about 150psig (1035 kPa) or less; about 100 psig (690 kPa) or less; or about 50psig (345 kPa) or less.

As will be appreciated, in integrating overall systems, while the one ormore heat exchangers 1010, 1016, 1018, 1020, 1022 and 1024 areillustrated as separate heat exchange devices, such heat exchangers maybe integrated into one or more integrated systems, where the differenttemperature process flows may be provided in thermal contact, e.g., asheat exchange media for each other, with in the heat exchange device orsystem. In particular, a cooled process flow that is desired to beheated may be passed through an opposing portion of a heat exchangerfrom a heated process flow that is desired to be cooled, such that theheat from the heated flow heats the cooler flow, and is, as a result,itself cooled.

Ethylene products of these processes, e.g., in C₂-rich effluent 1052,are then subjected to additional processing to yield the desired higherhydrocarbon compositions. For ease of discussion, the processes andsystems for converting ethylene into higher hydrocarbons are referred togenerally as ethylene conversion processes and systems. A number ofexemplary processes for ethylene conversion are described in greaterdetail herein.

ETL Integration with Hydrocarbon Processes

The conversion of methane to ethylene, as well as the conversion ofethylene to higher hydrocarbon compositions, can be carried out inintegrated processes. In some cases, conversion of ethylene to higherhydrocarbons is performed without conversion of methane to ethylene. Asused herein, integrated processes refers to two or more processes orsystems that are fluidly integrated or coupled together. Thus, theprocess for conversion of methane to ethylene can be fluidly connectedto one or more processes for ethylene conversion to one or more higherhydrocarbon compounds. Fluid integration or fluid coupling generallyrefers to a persistent fluid connection or fluid coupling between twosystems within an overall system or facility. Such persistent fluidcommunication typically refers to an interconnected pipeline networkcoupling one system to another. Such interconnected pipelines may alsoinclude additional elements between two systems, such as controlelements, e.g., heat exchangers, pumps, valves, compressors,turbo-expanders, sensors, as well as other fluid or gas transport and/orstorage systems, e.g., piping, manifolds, storage vessels, and the like,but are generally entirely closed systems, as distinguished from twosystems where materials are conveyed from one to another through anynon-integrated component, e.g., railcar or truck transport, or systemsthat are not co-located in the same facility or immediately adjacentfacilities. As used herein, fluid connection and/or fluid couplingincludes complete fluid coupling, e.g., where all effluent from a givenpoint such as an outlet of a reactor, is directed to the inlet ofanother unit with which the reactor is fluidly connected. Also includedwithin such fluid connections or couplings are partial connections,e.g., where only a portion of the effluent from a given first unit isrouted to a fluidly connected second unit. Further, although stated interms of fluid connections, it will be appreciated that such connectionsinclude connections for conveying either or both of liquids and/or gas.

In some instances, a methane to ethylene conversion process is not justintegrated with a single ethylene conversion process, but instead, isintegrated with multiple (i.e., two or more) different ethyleneconversion processes or systems. In particular, ethylene produced from asingle methane feed stream may be converted to multiple differentproducts using multiple different ethylene conversion processes. Forexample, in some embodiments a single OCM reactor system is fluidlyconnected to one, two, three, four, five or more different catalytic orother reactor systems for further conversion of the ethylene containingproduct of the OCM reactor system (also referred to herein as the“ethylene product”) to multiple different higher hydrocarboncompositions.

In some aspects, the ethylene product is selectively directed in wholeor in part to any one or more of the various ethylene conversionprocesses or systems integrated with the OCM reactor system. Forexample, at any given time, all of the ethylene product produced throughan OCM reactor system may be routed through a single process.Alternatively, a portion of the ethylene product may be routed through afirst ethylene conversion process or system, while some or all of theremaining ethylene product is routed through one, two, three, four ormore different ethylene conversion systems.

Although described in terms of directing ethylene streams to a single ormultiple different ethylene conversion processes, in some aspects, thoseethylene streams may be relatively dilute ethylene streams, e.g., thatcontain other components in addition to ethylene, such as other productsof the OCM reaction, unreacted feed gases, or other by products.Typically, such other components may include additional reactionproducts, unreacted feedgases, or other reactor effluents from anethylene production process, e.g., OCM, such as methane, ethane,propane, propylene, CO, CO₂, O₂, N₂, H₂, and/or water. The use of diluteethylene streams, and particularly those containing other hydrocarboncomponents can be particularly advantageous in the ethylene conversionprocesses. In particular, because these ethylene conversion processescan utilize more dilute and less pure streams, the incoming ethylenestreams may not be required to go through as stringent a separationsprocess or processes as may be required for other processes intended toproduce higher purity ethylene, e.g., cryogenic separations systems,lean oil separators, TSA and PSA based separations processes. Theseseparations processes typically have relatively high capital costs thatscale, at least in part, based upon the volume of incoming gases. Assuch, separation processes for highly dilute ethylene streams can havesubstantially high capital and operating costs associated with them. Byproviding less stringent separations requirements on these ethylenestreams, one can substantially reduce the capital costs. Further,because the ethylene conversion processes used in conjunction with theinvention typically result in the production of desired liquidhydrocarbons, subsequent separation of gas co-products, or unreactedfeed gases is made much simpler.

In addition to reducing capital and operating costs, the use of ethylenestreams that comprise additional hydrocarbon components can enhance theproduct slate emanating from the ethylene conversion processes throughwhich those ethylene streams are routed. In particular, the presence ofhigher order hydrocarbons, C₃, C₄, C₅, etc. in the ethylene streamsentering into the ethylene conversion processes can improve the overallefficiency of those processes, by providing enriched starting materials,and also affects the overall carbon efficiency of the OCM and ethyleneconversion processes, by ensuring that a greater fraction of the carboninput is converted to higher hydrocarbon products.

While ethylene streams being routed to the ethylene conversion processesof the invention may range anywhere from trace concentrations ofethylene to pure or substantially pure ethylene, e.g., approaching 100%ethylene, the dilute ethylene streams described herein may generally becharacterized as having anywhere from about 1% to about 50% ethylene,preferably, between about 5% and about 25% ethylene, and in furtherpreferred aspects, between about 10% and about 25% ethylene, in additionto other components. In other embodiments, the ethylene feed gascomprises less than about 5% ethylene, for example less than about 4%,less than about 3%, less than about 2% or even less than about 1%ethylene. In some embodiments, the dilute ethylene product gasesemployed in the ethylene conversion processes further comprise one ormore gases which are either produced during the OCM reaction or areunreacted during the OCM process. For example, in some embodiments theproduct gas comprises ethylene at any of the foregoing concentrationsand one or more gas selected from CO₂, CO, H₂, H₂O, C₂H₆, CH₄ and C₃₊hydrocarbons. In some embodiments, such dilute ethylene feed gasses,which optionally include one or more of the foregoing gases areadvantageous for use in reactions comprising conversion of ethylene tohigher olefins and/or saturated hydrocarbons, for example conversion ofethylene to liquid fuels such as gasoline diesel or jet fuel at higherefficiencies (e.g., from methane) than previously attainable.

By utilizing dilute ethylene streams to feed into one or more ethyleneconversion processes, one eliminates the need to separate or purify theethylene coming into the process, e.g., as a product of an OCM reactionprocess. The elimination of additional costly process steps isparticularly useful where the ethylene conversion processes are used toproduce lower margin products, such as gasoline, diesel or jet fuel orblendstocks for these fuels. In particular, where the desired product isa lower value product, one may pass the OCM feed gases directly into oneor more ethylene conversion processes that produce hydrocarbon mixturesthat can be used as gasoline, diesel fuel or jet fuel or theirblendstocks. Such direct passage may be in the absence of anyintermediate purification steps, such as any processes used for theremoval of the above described impurities. Alternatively, it may includecertain purification steps to separate out some or all of thenon-hydrocarbon impurities, e.g., N₂, CO₂, CO, H₂, etc. The directpassage may avoid any hydrocarbon fractionation, including removal ofany of C₁, C₂, C₃, C₄ compounds, or it may include some fractionation,e.g., to enhance carbon efficiency. For example, such includedfractionation may include separation of methane and or ethane from theOCM effluent gas to recycle back to the OCM process. In addition to theforegoing, the presence of additional components such as CO₂, H₂O and H₂in the feed streams may also be expected to improve catalyst lifetime inthe ethylene conversion processes by reducing deactivation, therebyrequiring fewer catalyst regeneration cycles.

In contrast, where one desires to produce more selectively purecompounds, e.g., aromatic compounds, one may need to pretreat the feedgases to remove many of the non-ethylene impurities.

Other components of these dilute ethylene streams may includeco-products of the ethylene production processes, e.g., OCM reactions,such as other C₂₊ hydrocarbons, like ethane, propane, propylene, butane,pentane, and larger hydrocarbons, as well as other products such as CO,CO₂, H₂, H₂O, N₂, and the like.

A variety of different ethylene conversion processes may be employed inthe various aspects of the present invention to produce higherhydrocarbon materials for use in, e.g., chemical manufacturing, polymerproduction, fuel production, as well as a variety of other products. Inparticular, the ethylene produced using the OCM processes may beoligomerized and/or reacted by a variety of different processes andreactor systems for producing linear alpha-olefins (LAOs), olefiniclinear and/or olefinic branched hydrocarbons, saturated linear and/orbranched hydrocarbons, saturated and/or olefinic cyclic hydrocarbons,aromatic hydrocarbons, oxygenated hydrocarbons, halogenatedhydrocarbons, alkylated aromatics, and/or hydrocarbon polymers.

In some cases, an ETL sub-system configured to perform an ethyleneconversion process (e.g., oligomerization) can be located between twoOCM sub-systems. A first OCM sub-system produces a first OCM effluentcomprising ethylene and other olefins (e.g., propylene). This first OCMeffluent can be fed into the ETL sub-system, wherein olefins (e.g.,ethylene, propylene) are oligomerized and converted into higherhydrocarbon products. These higher hydrocarbon oligomerization productscan be recovered from the ETL effluent. The ETL effluent can be fed intoa second OCM sub-system, where unreacted methane can be converted intoethylene and other olefins (e.g., propylene) in a second OCM process.The reduced content of C₂ and C₃ compounds in the second OCM feed stream(due to the consumption of C₂ and C₃ compounds in the ETL oroligomerization process) can result in decreased OCM side reactions andincreased C₂ selectivity in the second OCM sub-system. The effluent fromthe second OCM sub-system can be processed in a variety of ways,including by separation in a separations system (e.g., a 3-way cryogenicseparations system). A separations system can be used to recovermethane, which can be recycled to the first or second OCM system, olefinproducts (e.g., ethylene, propylene), and gases such as N₂, CO, and H₂.

ETL processes can result in products such as C₃ and C₄ products,including olefins. Rather than being flared or used for fuel value,these light olefins can be oligomerized into higher-value products. C₃olefins, C₄ olefins, or a combination thereof can be recovered from anETL product stream as a light olefin fraction. This light olefinfraction can be reacted in a separate oligomerization reactor to producehigher molecular weight olefins, such as those in the C₆ to C₁₆ range.The molecular weight range of the oligomerization products can be tunedby appropriate choice of catalyst and process parameters. This approachprovides the benefit of increased yield of higher molecular weightproducts, including products that are non-aromatic and mostly olefinic.This oligomerization process can result in little or no coke formationor other deactivation mechanisms. This oligomerization process canoperate at a temperature of at least about 50° C. This oligomerizationprocess can operate at a temperature of at most about 200° C. Thisoligomerization process can operate at a temperature from about 50° C.to about 200° C. Oligomerization catalysts useful for this processinclude strong Lewis acid catalysts, AlCl₃/water solutions, solidsuperacids, and other solid acid catalysts capable of oligomerizing C3and C4 olefins. C4 olefins in this process can also be used with analkylation process to generate iso-octane. Reactor configurations usefulfor this process include slurry bed, fixed bed, tubular/isothermal,moving bed, and fluidized bed reactors, including those disclosed herein(e.g., FIG. 4).

OCM processes, ETL processes, and combinations thereof (e.g., OCM-ETL)can result in methane (e.g., unreacted methane), ethane, and C₃₊non-olefinic hydrocarbon compounds. These compounds (e.g., methane,ethane, propane, and combinations thereof) can be converted intoaromatic hydrocarbons. For example, excess methane and ethane from anOCM process can be converted into aromatics with the use of a catalystappropriate for ETL, such as those discussed in this disclosure. Suchcatalysts can be doped with compounds including but not limited tomolybdenum (Mo), gallium (Ga), tungsten (W), and combinations thereof.These conversions to aromatic products can occur in an ETL reactor, asdescribed, and can also involve the conversion of ethylene to aromaticproducts.

Integration of ETL and/or OCM-ETL with Hydrocarbon Processes

The present disclosure provides methods for integrating ETL sub-systems(or modules) with OCM sub-systems. Such integration can advantageouslyenable the formation of products that can be tailored for various uses,such as, for example fuel. Such integration can enable the conversion ofethylene in a C₂₊ product stream from an OCM reactor to be converted tohigher molecular weight hydrocarbons.

OCM, ETL and OCM-ETL methods and systems of the present disclosure canbe used in greenfield and brownfield contexts. For example, in abrownfield investment initiative, an OCM-ETL system can be installed inan old oil refinery. As another example, in a greenfield investmentinitiative, an OCM-ETL system can be installed in a new parcel of roundthat has access to natural gas. Brownfield and greenfield initiatives ofOCM can be used to meet world scale production of ethylene.

The present disclosure can be used to form ethylene for various uses,such as liquefied natural gas (LNG) integration. Liquefied natural gas(LNG) can be used to enable simplified transport of natural gas with itsvolume reduced by at least about 100×, 200×, 300×, 400×, 500×, or 600×as enabled by cooling from a vapor to a liquid. LNG facilities caninclude several main process areas—gas treatment area where natural gashas acid gases, water, and mercury removed; NGL extraction area; NGLfractionation area; and LNG liquefaction and storage areas. C₄₊ productsfrom raw natural gas are typically recovered in the fractionation area.

Substantial capital reduction and improved mixed C₄ and C₅₊ yields canbe realized by integrating an OCM/ETL process train into the traditionalLNG facility. An OCM-ETL process may be added to LNG facility such thatit utilizes a portion of the main gas stream that has passed through gastreatment and NGL extraction. Additional feedstock to the post-bedreactor section of the OCM may include ethane and propane both fed fromhigh purity streams generated in the NGL fractionation area. Thegenerated additional mixed C₄ and C₅₊ products can be recovered thoughusing available capacity in the NGL fractionation process area. The C₄and C₅₊ products can be referred to as “SBOB,” which may be anycomposition similar to RBOB but not meeting one or more ASTM standards.

Alternatively, the process may utilizes the above gas streams (main gasstream, ethane and propane from fractionation area) in addition to adilute methane containing stream produced by the nitrogen rejection unitin the LNG liquification area. LNG plants can utilize this stream as lowBTU fuel gas for internal energy generation. The product gas from theOCM-ETL process area can be fed back into precool portion of the NGLextraction thus enabling proper extraction of the C₃₊ components as wellas generation of a similar low BTU fuel gas. The mixed C₄ and C₅₊ (SBOB)products can be recovered though using available capacity in the NGLfraction process area.

In an example, an OCM-ETL process area can include OCM reaction and heatrecovery areas, process gas compression, ETL guard bed and reactionsection. Steam generated in the OCM heat recovery area can beeffectively used in a refrigerant compressor area to reduce externalpower usage.

An OCM-ETL system can be integrated with an LNG facility. To meet theLNG specification any heavy hydrocarbon (HHC) (e.g., butanes, pentanesand higher molecular weight) in the natural gas stream may be removed.However, with the natural gas being dry, it may be difficult to removethe HHC. Hence an LNG plant may require some HHC removal process. Insome examples, liquids from an ETL system can be extracted in thepre-cooling process section of the LNG plant, requiring little to noadditional investment. This may eliminate any additional NGL recoverysystem that may be required in a standalone OCM/ETL facility. Inaddition, a large amount of steam can be produced in the OCM/ETL systemwhich can be effectively utilized as shaft power for the refrigerantcompressors. FIG. 11 shows an example of NGL extraction in an LNGfacility. The front-end NGL extraction unit 1100 can take natural gas1105 and separate out the natural gas liquids (NGLs) 1110. The remainingmethane 1115 can be compressed 1120 and cooled 1125 to provide liquifiednatural gas (LNG) 1130.

FIG. 12 shows an integrated OCM-ETL system for use in LNG production.The system includes a gas treatment unit, a downstream NGL extractionunit, a liquefaction unit, and an OCM/ETL sub-system that generatesolefins, such as ethylene. The direction of fluid flow is indicated bythe arrows. The system of FIG. 12 can provide increased C₅₊ and mixed C₄production. The system of FIG. 12 is exemplary of a typical gasprocessing plant 1200, with an OCM-ETL integration. The system containsa gas treatment unit 1202 which takes the incoming natural gas feedstream 1201. The gas treatment unit can comprise one or more of an acidgas removal unit, a dehydration unit, mercury removal unit, sulfurremoval unit, or other treatment units. In some cases the acid gasremoval unit is an amine unit, a pressure swing adsorption (PSA) unit,or another CO₂ removal system. In some cases, the dehydration unit canbe a glycol based water removal unit, a pressure swing adsorption (PSA)unit and may include a series of separators. A mercury removal unit cancomprise a molecular sieve or an activated carbon based system. The gastreatment unit can also comprise a nitrogen removal unit (NRU). An NRUcan employ a cryogenic process or an absorption or an adsorption basedprocess. The treated natural gas feed 1203 is fed to the NGL extractionunit 1204, which separates the NGL stream 1205 and a condensate streamcontaining heavier hydrocarbons 1210. The heavier hydrocarbons may beC₄₊ hydrocarbons. The NGL extraction unit can comprise an adsorptionprocess unit, a cooling unit (cooling achieved, for example, either byJoule Thompson expansion, methanol or glycol refrigeration, or aturboexpander), or a lean oil absorption unit. A part of the stream 1205is fed to the OCM-ETL reactor system 1207 as stream 1208, where themethane contained in the stream 1208 is converted to heavier liquidhydrocarbons via OCM and subsequent ETL conversion in the reactor system1207. The liquid hydrocarbons are fed along stream 1209 back to the NGLextraction unit to recover the unconverted methane, and separate theheavier condensates and route them along stream 1210 to NGL ETLfractionation unit 1211. The NGL ETL fractionation unit can comprise aseries of fractionation tower units, including but not limited to adepropanizer and a debutanizer to generate a mixed C₄ product 1214, aC₅₊ product 1215. The liquefaction unit 1206 produces LNG product 1213.The advantage of integrating an OCM-ETL reactor system with an existingnatural gas processing plant is envisaged in this case to generate muchmore valuable mixed C₄ and C₅₊ products. In addition, the C₂ and C₃lighter hydrocarbons from the fractionation unit 1211 can be recycled tothe post bed cracking (PBC) section of the OCM reactor.

The system of FIG. 12 can be modified for use with a diluted C₁(methane) fuel gas stream, as shown in FIG. 13. The system 1300 of FIG.13 includes a pre-cooling system 1320 upstream of the NGL extractionunit to extract C₃₊ compounds, as well as a nitrogen rejection unit 1316downstream of the liquefaction unit. In addition to the system of FIG.12, the system in FIG. 13 recycles a stream 1319 to the OCM-ETL reactorsystem to utilize more of the methane contained in the natural gas feed.The stream 1319 can comprise a high level of methane and inerts such asnitrogen. A fuel gas stream 1321 is purged from the precooling sectionto avoid the buildup of inerts in the system. The nitrogen rejectionunit can comprise a cryogenic based, absorption based or adsorptionbased system.

FIG. 14 shows an example OCM-ETL system comprising OCM and ETLsub-systems, and a separations sub-system downstream of the ETLsub-system, where 1418 is a condensed water knockout, 1421 is a processgas compressor, 1423 is a guard bed to remove impurities such asacetylene and butadiene, 1415 and 1430 are heat recovery, 1437 is asecondary gas compressor, and 1439 is a low temperature separator. Thesystem in FIG. 14 takes in a treated natural gas feed stream 1410 andoxygen 1411 from an air separation unit (ASU) or pipeline, and reactsthem in the OCM reactor 1413 to generate an olefin rich stream 1414which is then sent to an ETL reactor 1425 to be converted to higherhydrocarbons. The system shows the various subsystems as thecompressors, heat recovery systems utilizing the high heat of reactionto generate steam and run the compressors on the steam produced. Thesystem can comprise a methanation reactor 1427 to convert any CO and CO₂produced back to methane, hence adding to the methane content of thesales gas. The separation subsystem 1403 can comprise a low temperatureseparator 1439 to generate lighter methane rich components. Thedebutanizer 1442 separates the heavy hydrocarbon condensate to a C₄ andC₅₊ product.

FIG. 15 shows an OCM-ETL system comprising OCM 1906 and ETL 1907sub-systems, and a cryogenic cold box 1504 downstream of the ETLsub-system. The OCM-ETL system includes various separations units forseparating C₃ 1521 and C₄ 1524 components from an ETL product out of theETL sub-system. The depropanizer 1521 generates a C₂-rich stream whichis recycled back to the sales gas export 1509. The C₂ recycle may alsobe added to the OCM-ETL reactor subsystem via a recycle stream 1522. Thedebutanizer produces a C₄ product 1525 and a C₅₊ product 1526.Refrigeration for the cryogenic cold box can be provided by natural gasexpansion 1502 from at least about 500 PSI, 600 PSI, 700 PSI, 800 PSI,900 PSI, 1000 PSI, 1500 PSI, or 2000 PSI. The system can also have amethanation reactor (not shown) to further increase the methaneconcentration of the sales gas product. FIG. 15 indicates an approach tothermally integrate the different streams in the unit. The system canhave an external refrigeration system to provide for the cryogenicrequirements of the unit.

FIG. 16 shows another OCM-ETL in an alternative configuration to thatshown in FIG. 14. The system allows for the recycle of various streamsto the OCM reactor to improve the overall conversion. The methane richstream 1648 from the low temperature separation unit 1437 and a C₂ richstream 1412 from the deethanizer 1619 are recycled to the sales gascompressor 1617 and the OCM reactor 1413 respectively. The incomingnatural gas feed 1610 is treated (to remove one or more of sulfur,mercury, water, or other components) in a treatment unit 1611 and thensent to the cryogenic unit 1613 to separate the heavier NGL liquids 1614which are fed to the deethanizer 1619. The deethanizer 1619 separatesthe lighter LNG product 1620 from heavier C₂₊ stream 1412. Feed to OCMis drawn after the cryogenic unit. As in the systems of FIG. 14 and FIG.15, the separations subsystem generates a C₄ and C₅₊ product.

It may be noted that the systems of FIG. 14, FIG. 15, and FIG. 16 can beintegrated with an existing gas processing plant where one or more ofthe existing subsystems can be utilized. The utilization may arise fromthe fact that the existing subsystems are no longer used, or have anadditional capacity available to allow for the integration.

OCM-ETL systems of the present disclosure can be integrated into andcombined into conventional NGL extraction and NGL fractionation sectionsof a midstream gas plant. Where NGLs in the gas stream are declining (orgas is dry), the deployment of OCM-ETL can utilize an existing facilityto produce additional liquid streams. The implementation of OCM-ETL canallow for the generation of on specification “pipeline gas.” Theproducts from the facility can be suitable for use (or on specificationor “spec”) as pipeline gas, gasoline product, hydrocarbon (HC) streamwith high aromatic content and mixed C₄ product.

An OCM-ETL integrated facility can reduce ethane and propane productquantities to alleviate pipeline (sales-gas) specification and liquidhandling constraints. Utilities and off-sites facilities can beeffectively utilized. For example steam produced in the process canoffset other shaft power requirements. The capacity of the OCM-ETLFacility can be varied and can be selected to best fit specificrequirements.

FIGS. 17-18 show examples of OCM-ETL midstream integration. Natural gas1701 from upstream can be fed to a gas treatment system 1702 and thetreated natural gas can be fed to an NGL extraction unit 1704. In FIG.17, C₂ and C₃ products 1705 from the NGL extraction unit 1704 can bedirected to an OCM-ETL system 1707 to generate olefins (e.g., ethylene)and liquids 1709 from the olefins. Any excess or extracted methane canbe directed for use as pipeline gas 1713. C₄₊ hydrocarbons 1710 from theNGL extraction unit can be directed to an NGL product fractionation unitfor separation in a separations system 1711 into mixed C₄ 1714 andC₅+1715 product streams, with light hydrocarbons 1712 recycled to theOCM-ETL system 1707. In the system 1800 of FIG. 18, methane from othernatural gas sources 1816 is directed to a gas conditioning unit 1817(e.g., to remove sulfur compounds) and subsequently directed to theOCM-ETL system 1707. Excess methane 1808 can be used as pipeline gas1713, as an additional feed 1806 into the OCM-ETL system, or both.Oxygen feed for an OCM unit in the OCM-ETL system can be provided fromair, such as using an air separation unit (e.g., cryogenic airseparation unit), or from an oxygen source, such as pipeline oxygen.

OCM-ETL systems provided herein can be integrated into a pipeline NGsource, or as part of a new gas processing plant installation that mayprovide a source of NG. NG can be provided from a NG pipeline and/orfrom a non-OCM process.

In some cases, gas that has been depleted of recoverable hydrocarbonliquids can be recompressed to a pressure from about 700 PSI to 1500PSI, or 800 PSI to 1300 PSI, or 900 PSI to 1200 PSI and returned to thepipeline from which it was initially skimmed. As an alternative or inaddition to, gas that has been depleted of recoverable hydrocarbonliquids can be recompressed as needed and piped to downstream ofcryogenic gas processing plant. As another alternative or in additionto, gas that has been depleted of recoverable hydrocarbon liquids maynot be recompressed and is piped to power plant. As another alternativeor in addition to, gas that has been depleted of recoverable hydrocarbonliquids can be recompressed as needed and is piped to ammonia plant foruse as synthesis gas blending feedstock. As another alternative or inaddition to, gas that has been depleted of recoverable hydrocarbonliquids can be recompressed as needed and piped to a methanol plant foruse as synthesis gas feedstock blending.

FIG. 19 shows OCM-ETL systems with various skimmer and recycleconfigurations, including a standalone skimmer (top left), a hostedskimmer (bottom left), a standalone recycle (top right), and a hostedrecycle (bottom right). Under the skimmer configurations, operation is aonce-through process (feed moves forward) where all feed streams exitthe system as product or effluent without recycle. Under the recycleconfigurations, some or all of the NG feed stream is exposed to the OCMcatalyst multiple times (feed moves backward). Such configurations canbe employed in stand-alone settings, in which all or substantially allunit operations are for OCM/ETL purposes, or hosted settings, in whichthe unit operations of an existing non-OCM system at least partiallysupport the OCM-ETL system. The configurations of FIG. 19 can be used towith a NG feed of at least about 10 millions of cubic feet per day(mmcfd), 20 mmcfd, 30 mmcfd, 40 mmcfd, 50 mmcfd, 100 mmcfd, 200 mmcfd,300 mmcfd, 400 mmcfd, 500 mmcfd, or 1000 mmcfd.

In some cases, depending on economic considerations, various separationsintensities may be utilized for additional liquid product recovery. Inan example, process gas that remains after a primary liquid recoverysection is not further processed and is returned. In another example,process gas that remains after primary liquid recovery is fed to a LowTemperature Separator (LTS) unit where additional hydrocarbon liquidsare recovered, such as C₄₊. Effluent gas from this LTS is then returned,such recycled as described elsewhere herein.

In some cases, process gas that remains after primary liquid recoverycan be fed to a coldbox-based cryogenic unit where additionalhydrocarbon liquids are recovered, such as C₄₊. This coldbox-basedcryogenic unit may not utilize deep cryogenic temperatures and may notrequire traditional unit operations of demethanizer and deethanizer.Effluent gas from this unit may then be returned as described elsewhereherein. In some situations, a debutanizer column may be installed toprovide RVP control of final C₄₊ product and the additional C₄ stream.

There are a number of scenarios where it may be necessary to flare gasfrom a midstream gas gathering and or gas processing facility. In somecases, gas from a midstream system can be burned due to operatingconstraints, production gas fluctuations that may result in capacitylimitations of gas gathering and processing facilities, feed gasconditions that may prevent the gas being processed and meet the gasspecifications, and/or process gas conditions that may not allowco-processing in a gas facility.

ETL systems of the present disclosure can be integrated in variousexisting systems, such as petroleum refineries and/or petrochemicalcomplexes. Such integration can be with or without OCM systems.

Petroleum refineries and petrochemical complexes may generate asignificant amount and number of purge and other waste gas streams thatmay be burned for power generation at fuel value due to their inabilityto further process or recover the hydrocarbons. These waste gas streamsmay contain a mixture of inert gases and hydrocarbons, such as olefinicspecies. An ETL process can be integrated into a refinery orpetrochemical complex such that it consumes one or several of theseolefinic streams and chemically converts them to higher value oligomers,such as mixed C4 and C₅₊ mixtures. A wide range of these ETL feedstockscan be generated within a refinery complex.

Several examples of waste gas streams with suitable olefins include,without limitation, absorber tower overhead product gas streamcontaining ethylene and propylene at moderate levels generated in thelight ends recovery process area or the deethanizer overhead streamcontaining similar olefins. Streams can be reacted individually orblended as desired to meet ETL reactor inlet gas requirements.

An ETL process can include feedstock gas treatment, process gascompression, ETL reaction and heat recovery sections and units. The ETLreactor effluent can be returned to the refinery separations units ifexisting unit operations and capacity are available. If no such capacityis available, a small ETL separations sub-system may be provided torecover the effluent C₄ and C₅₊ product streams using a range of processintensity separations methods—cooling water or refrigerated condensationrecovery, sponge oil systems, and shallow-grade cryogenic units for thedeepest recovery. Additional process units may be added for furtherchemical recovery benefits, including membrane separations to recoveredhydrogen from the ETL reactor effluent post hydrocarbon recovery.

FIGS. 20-22 show various examples of ETL integration in refineries. Suchsystems can employ existing fractionation systems of refineries toeffect product separation.

With reference to FIG. 20, gas from cracking or other units 2001 is, ina refinery gas plant 2002, generated into C₃ and C₄ products 2004 thatare directed to an ETL system 2005, which generates higher molecularweight hydrocarbons 2006 that are directed to a product separationsystem 2007. The product separation system 2007 can employ an existingseparation system of the refinery. The direction of fluid flow andseparations systems can be selected to effect a given productdistribution, such as a C²⁻ fuel gas 2008, a C₃ product 2009, and a C₄₊stream 2010. The products 2013 from the fractionation unit 2011 can betreated to produce a gasoline blend component 2017 and the heavierproducts 2012 can be sent to the refinery aromatics separation unit2016. Ample integration/blending opportunities exist in a typicalrefinery complex.

The systems of FIG. 20 can include a heat exchange ethane cracker (HXEC)2119, as shown in FIG. 21. The HXEC can use heat from flue-gas 2118 tocrack ethane to ethylene. The HXEC can utilize one or more waste heatstream (as during FCC regeneration stage) to thermally crack the ethaneto generate an additional olefin rich stream as a feed to the ETLreactor. In some cases, the concept can be used to crack propane feed toproduce an olefin rich stream. For example, removal of coke fromcatalyst by combustion can generate a hot flue gas, in some cases withthe use of a co-boiler. Flue gas can reach temperatures of 1600° F.(˜870° C.), 1800° F. (˜980° C.), or higher. Heat can be transferred to astream comprising ethane, propane, or a combination thereof, for examplein a heat exchanger. This heat can be used to crack the ethane toethylene or the propane to propylene. These olefin products can be usedin other processes, such as in ETL.

A refinery gas plant 2202, receiving gas 2201 from cracking or otherunits, can be retrofitted with an OCM-ETL system, as shown in FIG. 22.The OCM reactor 2212 includes a post-bed cracking (PBC) unit. The OCMreactor 2212 accepts methane through a natural gas feed 2211 andgenerates a product stream 2213 that is directed to a C₁ separator 2207that removes methane (C₁) 2208 from the product stream to provide C₂₊compounds 2214. The methane can be recycled to the OCM reactor 2210 ordirected for use as refinery fuel 2209. C₂₊ compounds 2214 directed tothe ETL reactor 2215 are used to generate higher molecular weighthydrocarbons 2216, which are directed to the refinery gas plant 2202.C₃₊ compounds 2204 from the refinery gas plant are directed to aproduction fractionation system 2217 for separation. The system of FIG.22 can include an HXEC 2223 coupled with the ETL reactor 2215. The HXECcan ethane 2222 to ethylene 2224, which can then be directed to the ETLreactor 2215. In some situations, the HXEC is precluded.

The integration of an ETL system into a refinery or petrochemicalfacility can include a cracker and in some cases be performed withoutOCM. This can enable polymer grade ethylene to be turned into gasoline,for example.

It is to be noted with respect to the disclosures above pertaining tosystems described in FIG. 17, FIG. 18, FIG. 19, FIG. 20, FIG. 21, andFIG. 22 that the descriptions are indicative and not limited to theconcepts and configurations represented. One or more of the followingcan be additionally integrated into systems such as those described: amethanation reactor, an ethane skimmer, and various heat integrationconfigurations and optimizations based on the refinery configuration,product demand and economics. An ETL reactor system, including anOCM-ETL reactor system, can be a versatile system with a wide range ofconfigurations to achieve economic value from the refinery off gases,waste gases and additional natural gas feed(s).

Ethylene-to-Liquids (ETL) Integration with Natural Gas Processing

An aspect of the present disclosure provides olefin-to-liquids systemsand methods. An olefin-to-liquids process can be integrated in a non-OCMprocess, such as a natural gas liquids (NGL) system. Theolefin-to-liquids process can be an ethylene-to-liquids (ETL) process.The ETL process can be part of an OCM system, which can generate olefins(e.g., ethylene) from methane and an oxidizing agent (e.g., O₂), asdescribed elsewhere herein. The olefins can be used as feedstock to oneor more ETL reactors for the conversion of olefins to higher molecularweight hydrocarbons, which can be in liquid form.

Natural-gas processing is typically a complex industrial process forcleaning raw natural gas by separating impurities and variousnon-methane hydrocarbons and fluids to produce pipeline quality drynatural gas. Most extracted natural gas can contain, to varying degrees,low molecular weight hydrocarbon compounds. Examples of such compoundsinclude methane (CH₄), ethane (C₂H₆), propane (C₃H₈) and butane (C₄H₁₀).When brought to the surface and processed into purified, finishedby-products, all of these are collectively referred to as NGL.

Natural-gas processing plants may purify raw natural gas from (a)underground gas fields and/or (b) from well heads with associated gas byremoving common contaminates, such as water, carbon dioxide (CO₂) andhydrogen sulfide (H₂S). Some of the substances which contaminate naturalgas have economic value and are further processed or sold. A fullyoperational plant can deliver pipeline-quality dry natural gas that canbe used as fuel by residential, commercial and industrial consumers.

In some embodiments, existing NGL processing and/or fractionationsystems can be integrated with OCM and ETL processes to produce varioushydrocarbons (which may be liquids), such as alkanes, alkenes, alkynes,alkoxides, aldehydes, ketones, acids (e.g., carboxylic acids),aromatics, paraffins, iso-paraffins, higher olefins, oligomers orpolymers. In some examples, such hydrocarbons include liquefiedpetroleum gas (LPG), reformulated gasoline blendstock for oxygenblending (RBOB), and/or gasoline (e.g., natural gasoline or premiumgasoline), and/or other hydrocarbon blendstocks commonly fed torefineries or blending terminals (e.g., condensate or diluent). LPG caninclude propane and butane, and can be employed as fuel in heatingappliances and vehicles.

ETL can be used to generate hydrocarbons for various end uses, such asgasoline for use in machinery (e.g., automobiles and aircraft). Productsof ETL processes of the present disclosure can be employed for use asgasoline or jet fuel blend stock, for example. In some examples, ETL canbe used to generate benzene, toluene, ethylbenzene, and xylenes (BTEX).

An ETL-gasoline process can have a heat of reaction from about 80KJ/mole to 100 KJ/mol. An adiabatic ETL reactor can have an inlettemperature of at least about 200° C., 210° C., 220° C., 230° C., 240°C., 250° C., 260° C., 270° C., 280° C., 290° C., 300° C., 310° C., 320°C., 330° C., 340° C., 350° C., 360° C., 370° C., 380° C., 390° C., 400°C., or 500° C. In the reactor, temperature can increase by at leastabout 50° C. to 150° C., 60° C. to 120° C., or 75° C. to 100° C., andprocess pressure can increase by at least about 1 bar, 2 bars, 3 bars, 4bars, 5 bars, 6 bars, 7 bars, 8 bars, 9 bars, 10 bars, 20 bars, 30 bars,40 bars or 50 bars (absolute).

In some cases, the primary products out of an ETL reactor are olefins,such as a pentene, hexene or heptene. However, other secondary productsare possible, such as aromatics and paraffins. In an example, an ETLproduct has a liquids distribution that is selective towards C5-C10hydrocarbons with a substantially low content of benzene and durene.Such a product may be employed for use as gasoline. In another example,an ETL product has a liquids distribution that is selective towardsBTEX.

In some examples, a raw natural gas (NG) feed stock can be directed toan OCM-ETL system to generate C₂₊ compounds for use in generating highermolecular weight hydrocarbons, such as hydrocarbon products described inthe context of FIG. 1. Such hydrocarbons products can be furtherprocessed for various end uses. For example, the hydrocarbon productscan include the constituents of gasoline, and can be combined withethanol for use as automobile fuel.

OCM-ETL systems of the present disclosure can be integrated with NGLsystems to produce NGLs and premium quality gasoline, as well as NGLassociated with natural gas feed or any other hydrocarbon gas feedstocks. In some examples, NGL processing and/or fractionation ormidstream gas facilities or systems can be integrated with an OCMreactor system, an ETL reactor system, separations units, compressionunits, methanation units and or other processing units, such as thosedescribed in U.S. patent application Ser. No. 14/099,614, filed on Dec.6, 2013, which is entirely incorporated herein by reference.

OCM-ETL systems of the present disclosure can advantageously enableexisting NGL processing systems to be retrofitted for use in producingvarious hydrocarbons in an efficient and economical fashion as comparedto other systems presently available. In some examples, existing NGLprocessing and/or fractionation plants are integrated with OCM-ETLsystems provided herein, in addition to other systems that may berequired for further processing. OCM-ETL Integration with NGL processingmay include a retrofit of recycle split vapor (RSV), gas sub-cooledprocess (GSP) processes or any gas processing technology. The OCM-ETLplant can include other systems that may be required for furtherprocessing. Existing NGL systems can be retrofitted with OCM-ETL systemsprovided herein and configured, for example, to yield a given productdistribution and/or yield. Such integration may consider the spare orfull capacity of an existing NGL processing plant to reduce the retrofitcapital investments and operating expenses. The OCM-ETL system can bedesigned to accommodate any spare capacity of the NGL processing plant,or to accommodate the NGL plant operating as an OCM/ETL plant at maximumcapacity. The feed (or input) to the OCM-ETL may be a quantity of freshnatural gas, residue gas, or sales gas (sales gas and pipeline gas arereferring to the same natural gas which means pipeline specification)that meets the OCM inlet gas specifications and the spare capacity ofthe NGL plant. A requisite amount of an oxidizing agent (e.g., air oroxygen) can be used in the OCM reactor(s) of the OCM-ETL system.

In some examples, the quantity of the NGL products from OCM-ETL systemsof the present disclosure is at least about 0.3, 0.5, 0.1, 1, 1.5, 2, 3,4, 5, 6, 7, 8, 9, or 10 gallons per 1000 standard cubic feet (SCF) ofinlet natural gas of inlet gas. In some cases, the quantity of the NGLproducts from OCM-ETL systems of the present disclosure is at leastabout 0.3, at least about 0.5, at least about 0.1, at least about 1, atleast about 1.5, at least about 2, at least about 3, at least about 4,at least about 5, at least about 6, at least about 7, at least about 8,at least about 9, or at least about 10 gallons per 1000 standard cubicfeet (SCF) of inlet natural gas of inlet gas. In some cases, thequantity of the NGL products from OCM-ETL systems of the presentdisclosure is at most about 0.3, at most about 0.5, at most about 0.1,at most about 1, at most about 1.5, at most about 2, at most about 3, atmost about 4, at most about 5, at most about 6, at most about 7, at mostabout 8, at most about 9, or at most about 10 gallons per 1000 standardcubic feet (SCF) of inlet natural gas of inlet gas. In some cases, thequantity of the NGL products from OCM-ETL systems of the presentdisclosure is in the range of 0.8 gallons to 1.5 gallons per 1000standard cubic feet (SCF) of inlet natural gas of inlet gas.

FIG. 23A shows an NGL process. The NGL system comprises a raw naturalgas feed stream 2301, an NGL system 2302 and a product stream 2303. Theraw natural gas feed stream 2301 comprises methane (CH₄) in addition toother chemicals (e.g., H₂O, CO₂ and H₂S). The NGL system 2302 cancomprise various processing equipment for refining the feed stream 2301to generate the product stream 2303 comprising one or more hydrocarbonproducts, such as methane, ethane, propane and/or butane. Suchprocessing equipment can include separations units, such as distillationcolumns. In some examples, the product stream 2303 comprises methane ata concentration (or purity) that is higher as compared to the feedstream 2301. The product stream 2303 can be directed to a natural gaspipeline for distribution of natural gas to end users.

In FIG. 23B, the NGL process of FIG. 23A has been retrofitted with anOCM-ETL system of the present disclosure. FIG. 23B shows the feed stream2301 directed into NGL system 2304. The NGL system 2304 can include atleast a subset or all of the equipment of the NGL system 2302 describedin the context of FIG. 23A. In an example, the NGL system 2304 is theNGL system 2302. The NGL system 2304 yields the product stream 2303 andan additional product stream 2305. The additional product stream 2305 isdirected to an OCM-ETL system 2306. The OCM-ETL system 2306 generatesproduct stream 2307, which can include C₂₊ compounds. In some examples,the product stream comprises C₃-C₁₂ hydrocarbons.

Although FIG. 23B shows an NGL process retrofitted with an OCM-ETLsystem, other non-OCM processes may be retrofitted with the OCM-ETLsystem. For example, the OCM-ETL system can be integrated in an oilrefinery, and products from crude oil refining may be directed to theOCM-ETL system for further processing.

FIG. 24 shows a system 2400 comprising an existing gas plant 2401 thathas been retrofitted with an OCM-ETL system 2402. The OCM-ETL system2402 may be used with ethylene or other olefins. A raw natural gas (NG)feed 2403 is directed into the existing gas plant 2401, which comprisesa treatment unit 2404, NGL extraction unit 2405, compression unit 2406and fractionation unit 2407. The NGL extraction unit 2405 can be ademethanizer unit, optionally a demethanizer unit incorporated with arecycle split vapor (RSV) retrofit or stand-alone unit. The treatmentunit 2404 removes water and CO₂ from the NG feed 2403 and directsnatural gas to the NGL extraction unit 2405. In some cases, thetreatment unit removes sulfur from the NG feed. The NGL extraction unit2405 removes methane, ethane, CO₂ and N₂ from the NG feed 2403, anddirects methane, ethane, CO₂ and N₂ to the compression unit 2406 alongfluid stream 2408. At least a portion of the methane from the fluidstream 2408 is directed along stream 2409 to an OCM reactor 2410 of theOCM-ETL system 2402. The compression unit 2406 compresses methane in thefluid stream 2408 and directs compressed methane to a natural gaspipeline 2411 for distribution of methane to end users.

With continued reference to FIG. 24, C₂₊ compounds from the NGLextraction unit 2405 are directed to the fractionation unit 2407, whichcan be a distillation column. The fractionation unit 2407 splits the C₂₊compounds into streams comprising various C₂₊ compounds, such as a C₂stream 2412 along with C₃ 2423, C₄ and C₅ streams. The C₂ stream 2412and/or C₃ stream 2423 can be directed to a post-bed cracking (PBC) unit2413 of the OCM-ETL system 2402. In some cases, C₃, C₄ and/or C₄₊compounds are directed to the PBC unit. Examples of post-bed cracking isdescribed in U.S. patent application Ser. No. 14/553,795, filed Nov. 25,2014, which is entirely incorporated herein by reference.

In the OCM-ETL system 2402, methane from the stream 2409 and air 2414are directed to the OCM reactor 2410. The OCM reactor 2410 generates anOCM product stream comprising C₂₊ compounds in an OCM process, asdiscussed elsewhere herein. C₂₊ alkanes (e.g., ethane) in the productstream, as well as C₂ alkanes in the C₂ stream 2412, may be cracked toC₂₊ alkenes (e.g., ethylene) in the post-bed cracking (PBC) unit 2413(which can be a downstream component of the OCM reactor 2410). Theproduct stream is then directed to a condenser 2415, which removes waterfrom the product stream. The product stream is then directed to acompression unit 2416 and subsequently a pressure swing absorption (PSA)unit 2417. The PSA separates N₂, CO, CO₂, H₂O, H₂ and some methane fromC₂₊ compounds in the product stream, and directs the C₂₊ compounds toone or more ETL reactors 2418 of the OCM-ETL system 2402. The streamcomprising nitrogen 2424 (and in some cases CH₄, CO₂, H₂O, H₂ and/or CO)can be fed into a fuel gas stream for use in generating power, burning,use as a thermal oxidizer. The C₂₊ compounds directed into the ETLreactor 2418 can include ethane, ethylene, propane, propylene, alongwith methane, CO, CO₂, H₂, N₂ and water. The ETL reactor 2418 generateshigher molecular weight hydrocarbons, such as C₄-C₁₂ (e.g., C₄₊ or C₅₊)compounds (e.g., butane, butylenes, pentane, hexane, etc.). A productstream from the ETL reactor 2418 is directed to another compression unit2419 and subsequently a vapor-liquid separator (or knock-out drum) 2420,which separates liquids (e.g., the C₅₊ compounds) from vapors (e.g.,methane) in the product stream and provides a product stream 2421comprising the C₅₊ compounds. Remaining compounds, including vapors(e.g., methane), are recycled to the feed stream 2403 along recyclestream 2422. Methane directed along stream 2422 can be directed to theOCM reactor 2410 for further C₂₊ product generation.

The OCM-ETL 2402 system can include one or more OCM reactor 2410. Forexample, the OCM reactor 2410 can be an OCM reactor train comprisingmultiple OCM reactors. In addition to, or as an alternative, the OCM-ETLsystem 2402 can include one or more ETL reactor 2418. For example, theETL reactor 2418 can be multiple ETL reactors in parallel, with each ETLreactor configured to generate a given hydrocarbon (see, e.g., FIG. 1).In some cases, C₃ and/or C₄ compounds can be taken from thefractionators and fed into a further downstream region of a post-bedcracking (PBC) reactor for olefin production.

The compression units 2406, 2416 and 2419 can each be a multistage gascompression unit. Each stage of such multistage gas compression unit canbe followed by cooling and liquid hydrocarbon and water removal.

The OCM-ETL system 2402 can be operated with other oxidizing agents,such as previously separated O₂ such as O₂ from a pipeline or as aproduct from an air separation unit (ASU). In the alternativeconfiguration of FIG. 25, an O₂ feed stream 414 is directed to the OCMreactor 2410. The O₂ feed stream 2514 can be generated, for example,using a cryogenic air separation unit (not shown), which separates airinto individual streams comprising O₂ and N₂. The system of FIG. 25further includes a methanation system 2523 (see below) that converts CO,CO₂ and H₂ from the vapor-liquid separator to methane, which can berecycled along stream 2422.

In the figures, the direction of fluid flow between units is indicatedby arrows. Fluid may be directed from one unit to another with the aidof valves and a fluid flow system. In some examples, a fluid flow systemcan include compressors and/or pumps, as well as a control system forregulating fluid flow, as described elsewhere herein.

Methanation Systems

Oxidative Coupling of Methane (OCM) is a process that may convertnatural gas (or methane) to ethylene and other longer hydrocarbonmolecules via reaction of methane with oxygen. Given the operatingconditions of OCM, side reactions can include reforming and combustion,which can lead to the presence of significant amounts of H₂, CO and CO₂in the effluent stream. Typical H₂ content in the effluent stream canrange between about 5% and about 15%, between about 1% and about 15%,between about 5% and about 10%, or between about 1% and about 5% (molarbasis). CO and CO₂ can each range between about 1% and about 5%, betweenabout 1% and about 3%, or between about 3% and about 5% (molar basis).In some cases, the ethylene and all the other longer hydrocarbonmolecules contained in the effluent stream are separated and purified toyield the final products of the process. This can leave an effluentstream containing the unconverted methane, hydrogen, CO and CO₂ andseveral other compounds, including low amounts of the product themselvesdepending on their recovery rates.

In some cases, this effluent stream needs to be recycled to the OCMreactor. However, if CO and H₂ are recycled to the OCM reactor alongwith methane, they can react with oxygen to produce CO₂ and H₂O, causingvarious negative consequences to the process including, but not limitedto: (a) an increase of the natural gas feed consumption (e.g., because alarger portion of it can result in CO₂ generation instead of productgeneration); (b) a decrease of the OCM per-pass methane conversion(e.g., because a portion of the allowable adiabatic temperature increasecan be exploited by the H₂ and CO combustion reactions instead of theOCM reactions); and an increase of the oxygen consumption (e.g., becausesome of the oxygen feed can react with CO and H₂ instead of methane).

In some instances, the effluent stream is exported to a natural gaspipeline (i.e., to be sold as sales gas into the natural gasinfrastructure). Given that specifications can be in place for naturalgas pipelines, the concentrations of CO, CO₂ and H₂ in the effluent canneed to be reduced to meet the pipeline requirements.

In some embodiments, the effluent stream may also be used as a feedstockfor certain processes that may require lower concentrations of H₂, COand CO₂.

Therefore, it can be desirable to reduce the concentration of H₂, CO andCO₂ in the OCM effluent stream, upstream or downstream of the separationand recovery of the final products. This can be accomplished usingmethanation systems and/or by separating H₂ and CO from the effluentstream (e.g., using cryogenic separations or adsorption processes). Thedisclosure also includes separating CO₂ from the effluent stream usingCO₂ removal processes, such as chemical or physical absorption oradsorption or membranes. However, these separation processes can requiresignificant capital investments and can consume considerable amounts ofenergy, in some cases making an OCM-based process less economicallyattractive.

Described herein are systems and methods for reducing CO, CO₂ and H₂concentration in a methane stream. The method comprises reacting thesecompounds to form methane in a reaction called methanation.

CO₂ and/or sulfur-containing compounds (e.g., H₂S) can be separated viaa CO₂ removal unit, such as, for example, an amine-based system, acaustic system or any other physical or chemical absorption oradsorption unit. CO and H₂ can be separated together with the methane ina cryogenic separator. If CO and H₂ are recycled to an OCM reactor alongwith methane, they can react with oxygen (e.g., pure O₂ or O₂ in air) toproduce CO₂ and H₂O, causing various negative consequences to theprocess, including, without limitation: (i) increase in natural gas feedconsumption and a decrease in C₂₊ product generation; (ii) decrease ofthe OCM per-pass methane conversion; and (iii) increase in oxygenconsumption. Given the potential negative effects of the presence of COand H₂ in a stream comprising methane, it may be preferable to minimizethe concentration of CO and H₂. In addition, by converting the CO and H₂back into methane, the carbon efficiency of the process can be increasedby recycling the methane to the OCM reactor or to the natural gaspipeline.

An aspect of the present disclosure provides a methanation system thatcan be employed to reduce the concentration of CO, CO₂ and H₂ in a givenstream, such as an OCM product stream as well as improve carbonefficiency. This can advantageously minimize the concentration of CO,CO₂ and H₂ in any stream that may be ultimately recycled to an OCMreactor. The methanation system can be employed for use with any systemof the present disclosure, such as the OCM-ETL system 302 describedabove.

In a methanation system, CO reacts with H₂ to yield methane via CO+3H₂→CH₄+H₂O. In the methanation system, CO₂ can react with H₂ to yieldmethane via CO₂+4 H₂→CH₄+2 H₂O. Such processes are exothermic andgenerate heat that may be used as heat input to other process units,such as heating an OCM reactor of a PBC reactor, or pre-heatingreactants, such as methane and/or an oxidizing agent (e.g., O₂) prior toan OCM reaction.

In some cases, to limit the heat release per unit of flow of reactants,methanation can be conducted on streams that contain CO, CO₂, H₂ and asuitable carrier gas. The carrier gas can include an inert gas, such as,e.g., N₂, He or Ar, or an alkane (e.g., methane, ethane, propane and/orbutane). The carrier gas can add thermal heat capacity and significantlyreduce the adiabatic temperature increase resulting from the methanationreactions.

In some examples, methane and higher carbon alkanes (e.g., ethane,propane and butane) and nitrogen are employed as carrier gases in amethanation process. These molecules can be present in an OCM process,such as in an OCM product stream comprising C₂₊ compounds. Downstreamseparation units, such as a cryogenic separation unit, can be configuredto produce a stream that contains any (or none) of these compounds incombination with CO and H₂. This stream can then be directed to themethanation system.

A methanation system can include one or more methanation reactors andheat exchangers. CO, CO₂ and H₂ can be added along various streams tothe one or more methanation reactors. A compressor can be used toincrease the CO₂ stream pressure up to the methanation operatingpressure, which can be from about 2 bar (absolute) to 60 bar, or 3 barto 30 bar. CO₂ can be added to the inlet of the system in order tocreate an excess of CO₂ compared to the amount stoichiometricallyrequired to consume all the available H₂. This is done in order tominimize H₂ recycled to OCM, which may not be preferable.

Given the exothermicity of the methanation reactions, a methanationsystem can include various methanation reactors for performingmethanation. In some cases, a methanation reactor is an adiabaticreactor, such as an adiabatic fixed bed reactor. The adiabatic reactorcan be in one stage or multiple stages, depending, for example, on theconcentration of CO, CO₂ and H₂ in the feed stream to the methanationsystem. If multiple stages are used, inter-stage cooling can beperformed by either heat exchangers (e.g., a stage effluent can becooled against the feed stream or any other colder stream available inthe plant, such as boiler feed water) or quenching via cold shots, i.e.the feed stream is divided into multiple streams, with one stream beingdirected to the first stage while each of the other feed streams beingmixed with each stage effluent for cooling purposes. As an alternative,or in addition to, a methanation reactor can be an isothermal reactor.In such a case, reaction heat can be removed by the isothermal reactorby, for example, generating steam, which can enable a higherconcentration of CO, CO₂ and H₂ to be used with the isothermal reactor.Apart from adiabatic and isothermal reactors, other types of reactorsmay be used for methanation.

FIG. 26 shows an example methanation system 2600. The system 2600comprises a first reactor 2601, second reactor 2602 and a heat exchanger2603. The first reactor 2601 and second reactor 2602 can be adiabaticreactors. During use, a recycle stream 2604 comprising methane, CO andH₂ (e.g., from a cryogenic separation unit) is directed to the heatexchanger 2603. In an example, the recycle stream 2604 comprises betweenabout 65% and 90% (molar basis) methane, between about 5% and 15% H₂,between 1% and 5% CO, between about 0% and 0.5% ethylene, and thebalance inert gases (e.g., N₂, Ar and He). The recycle stream 2604 canhave a temperature from about 20° C. to 30° C., and a pressure fromabout 2 bar to 60 bar (absolute), or 3 bar to 30 bar. The recycle stream2604 can be generated by a separation unit downstream of an OCM reactor,such as a cryogenic separation unit.

In the heat exchanger 2603, the temperature of the recycle stream 2604is increased to about 100° C. to 400° C., or 200° C. to 300° C. Theheated recycle stream 2604 is then directed to the first reactor 2601.In the first reactor 2601, CO and H₂ in the recycle stream 2604 react toyield methane. This reaction can progress until all of the H₂ isdepleted and/or a temperature approach to equilibrium of about 0 to 30°C., or 0 to 15° C. is achieved. The methanation reaction in the firstreactor 2601 can result in an adiabatic temperature increase of about20° C. to 300° C., or 50° C. to 150° C.

Next, products from the first reactor, including methane and unreactedCO and/or H₂, can be directed along a first product stream to the heatexchanger 2603, where they are cooled to a temperature of about 100° C.to 400° C., or 200° C. to 300° C. In the heat exchanger 2603, heat fromthe first product stream 2603 is removed and directed to the recyclestream 2604, prior to the recycle stream 2604 being directed to thefirst reactor 2601.

Next, a portion of the heated first product stream is mixed with a CO₂stream 2605 to yield a mixed stream that is directed to the secondreactor 2602. The CO₂ stream 2605 can be generated by a separation unitdownstream of an OCM reactor, such as a cryogenic separation unit. Thiscan be the same separation unit that generated the recycle stream 2604.In some cases, the methods described herein increase carbon efficiencycompared to methods that do not use methanation. For example, the amountof CO and/or CO₂ can be reduced by at least about 5%, at least about10%, at least about 20%, at least about 50%, at least about 75% or atleast about 80%.

In the second reactor 2602, CO and CO₂ react with H₂ to yield a secondproduct stream 2606 comprising methane. The reaction(s) in the secondreactor 2602 can progress until substantially all of the H₂ is depletedand/or a temperature approach to equilibrium of about 0 to 30° C., or 0to 15° C. is achieved. The proportions of CO, CO₂ and H₂ in the mixedstream can be selected such that the second product stream 2606 issubstantially depleted in CO and H₂. In some cases, the second productstream 2606 is fed back into the natural gas feed of a natural gas toliquids facility.

The first reactor 2601 and the second reactor 2602 can be two catalyticstages in the same reactor vessel or can be arranged as two separatevessels. The first reactor 2601 and second reactor 2602 can each includea catalyst, such as a catalyst comprising one or more of ruthenium,cobalt, nickel and iron. The first reactor 2601 and second reactor 2602can be fluidized bed or packed bed reactors. Further, although thesystem 2600 comprises two reactors 2601 and 2602, the system 2600 caninclude any number of reactors in series and/or in parallel, such as atleast 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, or 50 reactors.

Although the CO₂ stream 2605 is shown to be directed to the secondreactor 2602 and not the first reactor 2601, in an alternativeconfiguration, at least a portion or the entire CO₂ stream 2605 can bedirected to the first reactor 2601. The proportions of CO, CO₂ and H₂can be selected such that the methanation product stream issubstantially depleted in CO and H₂.

Methane generated in the system 2600 can be employed for various uses.In an example, at least a portion of the methane can be recycled to anOCM reactor (e.g., as part of an OCM-ETL system) to generate C₂₊compounds, including alkenes (e.g., ethylene). As an alternative, or inaddition to, at least a portion of the methane can be directed to anon-OCM process, such as a natural gas stream of a natural gas plant(see, e.g., FIGS. 3 and 4). As an alternative, or in addition to, atleast a portion of the methane can be directed to end users, such asalong a natural gas pipeline.

The methanation reaction can be practiced over a nickel-based catalyst,such as those used to produce SNG (Substitute Natural Gas or SyntheticNatural Gas) from syngas or used to purify streams containing CO and CO₂(e.g., to remove CO and CO₂ present in the make-up feed to an ammoniasynthesis unit). Examples of such catalysts include the KATALCO™ series(including models 11-4, 11-4R, 11-4M and 11-4MR) that are include nickelsupported on refractory oxides; the HTC series (including NI 500 RP 1.2)having nickel supported on alumina; and Type 146 having rutheniumsupported on alumina. Additional methanation catalysts include modelsPK-7R and METH-134. The methanation catalyst can be tableted or anextrudate. The shapes of such catalysts can be, for example,cylindrical, spherical, or ring structures, or partial shapes and/orcombinations thereof. In some cases, ring structures are advantageousdue to their reduced pressure drop across the reactor bed relative tocylindrical and spherical commercial forms. In some cases, themethanation catalyst is a doped or modified version of a commerciallyavailable catalyst.

In some cases, merely applying a methanation catalyst to the OCM and/orETL process that has been developed or optimized for another process(e.g., SNG production or gas purification) can result in operationalproblems and/or non-optimal performance, including carbon formation (orcoking) over the methanation catalyst. Coking can lead to de-activationof the catalyst and, eventually, to loss of conversion through themethanation reactor, thus making the methanation process ineffective,severely limiting the performances of the overall OCM and/or ETL-basedprocess and, possibly, preventing the final products from achieving therequired specifications.

The selectivity and/or conversion produced by an existing and/orcommercially available methanation catalyst at a given process condition(e.g., gas-hourly space velocity, molar composition, temperature,pressure) may not be ideal for OCM and/or ETL implementations. Forexample, ammonia plants can have between about 100 ppm and 1% CO with amolar excess of H₂ (e.g., 2, 5, 10, 50, 100-fold or more excess) thatdrives equilibrium in favor of complete methanation. Methanation systemsin ammonia plants have a small temperature difference between inlet andoutlet of the adiabatic methanation reactor (e.g., 20 to 30° C.) and canbe sized for catalyst lifetime. SNG production does not have a vastmolar excess of H₂ in some cases. Methanation in SNG processes can havean inlet versus outlet temperature difference of greater than 100° C.and be performed in multiple stages. Furthermore, the purpose ofmethanation can be different for OCM and/or ETL. Ammonia and SNGprocesses typically perform methanation primarily to eliminate CO and/orCO₂ (although H₂ can also be eliminated or substantially reduced inconcentration), while methanation is performed in OCM and/or ETLprocesses primarily to eliminate H₂ (although CO and/or CO₂ can also beeliminated or substantially reduced in concentration).

A methanation catalyst and/or catalytic process is described herein thatcan prevent or reduce carbon formation in the methanation reactor orother operational inefficiencies. The catalyst and/or catalytic processcan be achieved through any combination of: (a) removing chemicalspecies that can contribute to coke formation from the methanation inletfeed; (b) introducing chemical species into the methanation feed thateliminate or reduce the rate of coke formation; and (c) using themethanation catalyst described herein that reduces or eliminates cokeformation and/or is designed to operate at the process conditions of OCMand/or ETL effluent or OCM and/or ETL process streams (e.g., gas-hourlyspace velocity, molar composition, temperature, pressure).

In some instances, the species present in the OCM and/or ETL effluentstream that can lead to carbon formation in the methanation reactor areremoved or reduced in concentration using a separations or reactiveprocess. The typical operating conditions of a methanation reactor canbe between about 3 and about 50 bar pressure and between about 150 andabout 400° C. temperature. Any hydrocarbon species containingcarbon-carbon double or triple bonds is sufficiently reactive to formcarbon deposits (i.e., coke). Examples of these species are acetylene,all olefins and aromatic compounds. Removal or significant reduction ofthese species can be achieved via different methods including, but notlimited to: (a) hydrogenation (i.e., reaction of these species with thehydrogen present in the effluent stream itself to produce alkanes) oversuitable catalysts prior to the methanation reactor; (b) condensationand separation of these species from methane prior to the methanationreactor; (c) absorption or adsorption of these species; (d) by utilizingsuitable membranes; or (d) any combination thereof.

In embodiments of the present disclosure, new species are introducedinto the methanation inlet stream that eliminate or reduce the rate ofcarbon formation. Molecular species that can create a reducingatmosphere can be used to counteract an oxidation reaction and cantherefore reduce the rate of carbon formation. Hydrogen and water areexamples of these particular compounds and can be added to the OCMand/or ETL effluent stream prior to methanation to increase theirconcentration in the methanation reactor.

An aspect of the present disclosure provides a methanation catalyst foran OCM and/or ETL process. Coke formation is typically the product ofsurface driven reactions. Therefore, the methanation catalyst for OCMand/or ETL alters the local electronic environment around the activesite of the catalyst. This can be done by changing the elementalcomposition (for example via post-impregnation doping, or creating a newmixed metal of nickel and another transition metal), morphology andstructure (for example via synthesizing the metal in a non-bulk formfactor). Examples of such syntheses include; nanowires of the samematerial, nanoparticles coated on a support, and vapor deposition of theactive material on a support material. Additional modifications to thesurface may result from post synthetic processing steps, such as etchingof the surface, oxidizing and reducing the metal to create a differentsurface reconstruction, calcination steps under different atmospheres(e.g., oxidizing or reducing), heating to achieve different crystalphases, and inducing defect formation. The end result of saidmodifications of the methanation catalyst is specifically designed tominimize carbon (coke) formation, while still effectively at conductingthe methanation reactions.

The methanation process and/or methanation catalyst operates with OCMand/or ETL product gas, either directly or after one or more heatexchangers or separation operations. For example, the methanation feedstream can have the following composition on a molar basis: CH₄ betweenabout 65% and about 90%; H₂ between about 5% and about 15%; CO betweenabout 1% and about 5% (molar basis); C₂H₄ between about 0% and about0.5%; and C₂H₂ between about 0% and about 0.1%. As described herein, theETL effluent can contain C₂₊ compounds including propane, propylene,butane, butylene, and C₅₊ compounds. These C₂₊ compounds can be presentin the stream entering the methanation reactor in any concentration. Thebalance of the feed stream can be inert gases such as N₂, Ar and He. Themethanation feed stream typically has a temperature close to ambienttemperature and a pressure ranging between about 3 and about 50 bar.

In some cases, the entire ETL product stream and/or all of the C₂₊compounds present in the ETL effluent and/or any or all of the olefinspresent in the ETL effluent are fed into the methanation reactor (i.e.,methanation feed). In some cases, the temperature of the ETL effluent isnot reduced, or not substantially reduced before being fed into themethanation reactor such that all or most (at least about 70%, at leastabout 80%, at least about 90%, at least about 95%, or at least about99%) of the C₂₊ compounds and/or olefins remain in the methanation feed.In some cases, the temperature of the ETL effluent is reduced toseparate some of the C₂₊ compounds and/or olefins from the stream beforebeing fed into the methanator. The temperature can be reduced to atemperature sufficiently low to remove most (at least about 70%, atleast about 80%, at least about 90%, at least about 95%, or at leastabout 99%) of the C₅₊ compounds (e.g., about 40° C.), to remove most (atleast about 70%, at least about 80%, at least about 90%, at least about95%, or at least about 99%) of the C₄₊ compounds (e.g., about 10° C.),or to remove most (at least about 70%, at least about 80%, at leastabout 90%, at least about 95%, or at least about 99%) of the C₃-+compounds (e.g., about −40° C.).

The methanation reaction can produce water and/or have water in themethanation effluent. In some cases, it can be desirable to remove thiswater prior to recycling the methanation effluent to the OCM reactor.This can be accomplished by lowering the temperature of the methanationeffluent or performing any separation procedure that removes the water.In some embodiments, at least about 70%, at least about 80%, at leastabout 70%, at least about 90%, at least about 95%, or at least about 99%of the water is removed from the methanation effluent prior to the OCMreactor. Removing the water can increase the lifetime and/or performanceof the OCM catalyst.

In some cases, the ETL process can be designed to use a methanationcatalyst that is not optimized for the ETL process. The OCM or OCM-ETLprocess can be designed to produce gasoline or distillates or aromatics(or any combination thereof) from natural gas. In this case, theeffluent of the OCM reactor is fed to an ETL reactor where all shortolefins (e.g., ethylene and propylene) are converted to longer chainhydrocarbons over a suitable oligomerization catalyst. An example ofsuch a catalyst is the zeolite ZSM-5. The product stream that containsunconverted methane, unconverted olefins, CO, CO₂, H₂, water, inertspecies and all oligomerization products (paraffins, isoparaffins,olefins and aromatics) is fed to the methanation module. Theconcentration of the oligomerization products in the methanation feedstream can vary depending on the type and extent of separation conductedprior to the methanation step. The methanation feed stream typically hasa temperature close to or below ambient temperature and a pressureranging between 3 and 50 bar.

With reference to FIG. 27, the methanation system can be designed to usea catalyst that is not necessarily optimized for the OCM and/or ETLprocess streams. The methanation feed stream 2700 is first sent to afirst heat exchanger 2705 where its temperature is increased to themethanation reactor inlet temperature, typically between 150 and 300° C.Steam is injected 2710 immediately downstream of the heat exchanger toincrease water concentration in the methanation feed stream. Then theheated stream is fed to a first adiabatic reactor 2715 where ethylene,acetylene and any other hydrocarbon that presents multiple carbon-carbonbonds are hydrogenated via reaction with the H₂ present in the streamitself.

The effluent from 2715 is then fed to a second reactor 2720, where COand CO₂ react with H₂ until a desired approach to equilibrium isachieved, typically 0-15° C. to equilibrium. The adiabatic temperatureincrease that results from CO and CO₂ methanation can depend on thecomposition of the feed stream, and is typically in the 50-150° C.range.

The effluent from the second reactor 2720 is then sent to the first heatexchanger 2705 and a second heat exchanger 2725 where it is cooled downto a temperature below water condensation. The stream is then fed to aphase separator 2730 where the condensed water and a portion of thelonger hydrocarbons is separated from the vapors.

The vapor stream from the phase separator 2735 is sent to the finalproduct purification and recovery section or injected into a natural gaspipeline, depending on its concentration. Alternatively, the vaporstream 2735 from the phase separator 2730 can be further methanated in asecond methanation reactor to further reduce CO, CO₂ and H₂concentration (not shown).

The liquid stream from the phase separator 2740 is re-injected into themethanation feed stream alongside the steam. Alternatively, it can befirst vaporized and then re-injected, or it can be sent to a watertreatment system for water recovery and purification (not shown).

The reactors 2715, 2720 (and a third reactor, if present) or anycombination of them can be physically situated in the same vessel or canbe arranged in separate individual vessels.

In processes, systems, and methods of the present disclosure, aFischer-Tropsch (F-T) reactor can be used to replace a methanationreactor, for example in a methane recycle stream. CO and H₂, such asthat found in a methane recycle stream, can be converted to a variety ofparaffinic linear hydrocarbons, including methane, in an F-T reaction.Higher levels of linear hydrocarbons, such as ethane, can improve OCMprocess efficiency and economics. For example, effluent from an OCMreactor can be directed through a cooling/compression system and otherprocesses before removal of a recycle stream in a de-methanizer. Therecycle stream can comprise CH₄, CO, and H₂, and can be directed into anF-T reactor. The F-T reactor can produce CH₄ and C₂₊ paraffins forrecycling into the OCM reactor. A range of catalysts, including anysuitable F-T catalyst, can be employed. Reactor designs, including thosediscussed in the present disclosure, can be employed. F-T reactoroperation conditions, including temperature and pressure, can beoptimized. This approach can reduce H₂ consumption compared to amethanation reactor.

Hydrocarbon Separations

In natural gas processing plants, methane can be separated from ethaneand higher carbon-content hydrocarbons (conventionally called naturalgas liquids or NGLs) to produce a methane-rich stream that can meet thespecifications of pipelines and sales gas. Such separation can beperformed using cryogenic separation, such as with the aid of one ormore cryogenic units.

The raw natural gas fed to gas processing plants can have a molarcomposition of 70% to 95% methane and 4% to 20% NGLs, the balance beinginert gas(ses) (e.g., CO₂ and N₂). The ratio of methane to ethane can bein the range of 5-25:1. Given the relatively large amount of methanepresent in the stream fed to cryogenic sections of gas processingplants, at least some or substantially all of the cooling duty requiredfor the separation is provided by a variety of compression and expansionsteps performed on the feed stream and the methane product stream. Noneor a limited portion of the cooling duty can be supplied by externalrefrigeration units.

There are various approaches for separating higher carbon alkanes (e.g.,ethane) from natural gas, such as recycle split vapor (RSV) and gassub-cooled process (GSP) processes, which can maximize the recovery ofethane (e.g., >95% recovery) while providing most or all of the coolingduty via internal compression and expansion of the methane itself.However, the application of such approach in separating alkenes (e.g.,ethylene) from an OCM product stream comprising methane may result in alimited recovery (e.g., provide less than 95% recovery) of the alkeneproduct, due at least in part to (i) the different vapor pressure ofalkenes and alkanes, and/or (ii) the presence of significant amounts ofH₂ in the OCM product stream, which can change the boiling curve and,particularly, the Joule-Thomson coefficient of the methane stream thatneeds to be compressed and expanded to provide the cooling duty.Hydrogen can display a negative or substantially low Joule-Thomsoncoefficient, which can cause a temperature increase or a substantiallylow temperature decrease in temperature when a hydrogen-reach stream isexpanded.

In some embodiments, the design of a cryogenic separation system of anOCM-based plant can feature a different combination ofcompression/expansion steps for internal refrigeration and, in somecases, external refrigeration. The present disclosure provides aseparation system comprising one or more cryogenic separation units andone or more de-methanizer units. Such a system can maximize alkenerecovery (e.g., provide greater than 95% recovery) from a streamcomprising a mixture of alkanes, alkenes, and other gases (e.g., H₂),such as in an OCM product stream (see FIGS. 24 and 25 and the associatedtext).

In such separation system, the cooling duty can be supplied by acombination of expansion of the OCM effluent (feed stream to thecryogenic section) when the OCM effluent pressure is higher than ade-methanizer column; expansion of at least a portion or all of thede-methanizer overhead methane-rich stream; compression and expansion ofa portion of the de-methanizer overhead methane-rich stream; and/orexternal propane, propylene or ethylene refrigeration units.

FIGS. 28-33 show various separation systems, as can be employed withvarious systems and methods of the present disclosure. Such systems canbe employed for use in the OCM-ETL systems described herein, such asused as the vapor-liquid separator 320 described above in the context ofFIGS. 3 and 4.

FIG. 28 shows a separation system 2800 comprising a first heat exchanger2801, a second heat exchanger 2802, a de-methanizer 2803, and a thirdheat exchanger 2804. The direction of fluid flow is shown in the figure.The de-methanizer 2803 can be a distillation unit or multipledistillation units (e.g., in series). In such a case, the de-methanizercan include a reboiler and a condenser, each of which can be a heatexchanger. An OCM effluent stream 2805 is directed to the first heatexchanger 2801 at a pressure from about 10 to 100 bar (absolute), or 20to 40 bar. The OCM effluent stream 2805 can include methane and C₂₊compounds, and may be provided in an OCM product stream from an OCMreactor (not shown). The OCM effluent stream 2805 is then directed fromthe first heat exchanger 2801 to the second heat exchanger 2802. In thefirst heat exchanger 2801 and the second heat exchanger 2802, the OCMeffluent stream 2805 is cooled upon heat transfer to a de-methanizeroverhead stream 2806, a de-methanizer reboiler stream 2807, ade-methanizer bottom product stream 2808, and a refrigeration stream2809 having a heat exchange fluid comprising propane or an equivalentcooling medium, such as, but not limited to, propylene or a mixture ofpropane and propylene.

The cooled OCM effluent 2805 can be directed to the de-methanizer 2803,where light components, such as CH₄, H₂ and CO, are separated fromheavier components, such as ethane, ethylene, propane, propylene and anyother less volatile component present in the OCM effluent stream 2805.The light components are directed out of the de-methanizer along theoverhead stream 2806. The heavier components are directed out of thede-methanizer along the bottom product stream 2808. The de-methanizercan be designed such that at least about 60%, 70%, 80%, 90%, or 95% ofthe ethylene in the OCM effluent stream 2805 is directed to the bottomproduct stream 2808.

The de-methanizer overhead stream 2806 can contain at least 60%, 65%, or70% methane. The overhead stream 2806 can be expanded (e.g., in aturbo-expander or similar machine or flashed over a valve or similardevice) to decrease the temperature of the overhead stream 2806 prior todirecting the overhead stream 2806 to the second heat exchanger 2802 andsubsequently the first heat exchanger 2801. The overhead stream 2806 canbe cooled in the third heat exchanger 2804, which can be cooled using areflux stream and a hydrocarbon-containing cooling fluid, such as, forexample, ethylene.

The overhead stream 2806, which can include methane, can be recycled toan OCM reactor and/or directed for other uses, such as a natural gaspipeline. In some examples, the bottom product stream, which can containC₂₊ compounds (e.g., ethylene), can be directed to an ETL system.

FIG. 29 shows another separation system 2900 that may be employed foruse with systems and methods of the present disclosure. The direction offluid flow is shown in the figure. The system 2900 comprises a firstheat exchanger 2901, de-methanizer 2902 and a second heat exchanger2903. The de-methanizer 2902 can be a distillation unit or multipledistillation units (e.g., in series). An OCM effluent stream 2904 isdirected into the first heat exchanger 2901. The OCM effluent stream2904 can include methane and C₂₊ compounds, and may be provided in anOCM product stream from an OCM reactor (not shown). The OCM effluentstream 2904 can be provided at a pressure from about 10 bar (absolute)to 100 bar, or 40 bar to 70 bar. The OCM effluent stream 2904 can becooled upon heat transfer to a de-methanizer overhead streams 2905 and2906 from the second heat exchanger 2903, a de-methanizer reboilerstream 2907, and a refrigeration stream having a cooling fluidcomprising, for example, propane or an equivalent cooling medium, suchas, but not limited to, propylene or a mixture of propane and propylene.In some cases, the de-methanizer overhead streams 2905 and 2906 arecombined into an output stream 2912 before or after passing through thefirst heat exchanger 2901.

Subsequent to cooling in the first heat exchanger 2901, the OCM effluentstream 2904 can be expanded in a turbo-expander or similar device orflashed over a valve or similar device to a pressure of at least about 5bar, 6 bar, 7 bar, 8 bar, 9 bar, or 10 bar. The cooled OCM effluentstream 2904 can then be directed to the de-methanizer 2902, where lightcomponents (e.g., CH₄, H₂ and CO) are separated from heavier components(e.g., ethane, ethylene, propane, propylene and any other less volatilecomponent present in the OCM effluent stream 2904). The light componentsare directed to an overhead stream 2909 while the heavier components(e.g., C₂₊) are directed along a bottoms stream 2910. A portion of theoverhead stream 2909 is directed to second heat exchanger 2903 andsubsequently to the first heat exchanger 2901 along stream 2906. Aremainder of the overhead stream 2909 is pressurized in a compressor anddirected to the second heat exchanger 2903. The remainder of theoverhead stream 2909 is then directed to a phase separation unit 2911(e.g., distillation unit or vapor-liquid separator). Liquids from thephase separation unit 2911 are directed to the second heat exchanger2903 and subsequently returned to the de-methanizer 2902. Vapors fromthe phase separation unit 2911 are expanded (e.g., in a turbo-expanderor similar device) and directed to the second heat exchanger 2903, andthereafter to the first heat exchanger along stream 2905. Thede-methanizer 2902 can be designed such that at least about 60%, 70%,80%, 90%, or 95% of the ethylene in the OCM effluent stream 2904 isdirected to the bottom product stream 2910.

FIG. 30 shows another separation system 3000 that may be employed foruse with systems and methods of the present disclosure. The direction offluid flow is shown in the figure. The system 3000 comprises a firstheat exchanger 3001, a de-methanizer 3002, a second heat exchanger 3003and a third heat exchanger 3004. The system 3000 may not require anyexternal refrigeration. The de-methanizer 3002 can be a distillationunit or multiple distillation units (e.g., in series). An OCM effluentstream 3005 is directed to the first heat exchanger 3001 at a pressurefrom about 10 bar (absolute) to 100 bar, or 40 bar to 70 bar. In thefirst heat exchanger 3001, the OCM effluent stream 3005 can be cooledupon heat transfer to de-methanizer overhead streams 3006 and 3007, ade-methanizer reboiler stream 3008 and a de-methanizer bottom productstream 3009. In some cases, the de-methanizer overhead streams 3006 and3007 are combined into a common stream 3015 before or after they arepassed through the first heat exchanger 3001. The OCM effluent stream3005 is then expanded to a pressure of at least about 5 bar, 6 bar, 7bar, 8 bar, 9 bar, or 10 bar, such as, for example, in a turbo-expanderor similar machine or flashed over a valve or similar device. The cooledOCM effluent stream 3005 is then directed to the de-methanizer 3002,where light components (e.g., CH₄, H₂ and CO) are separated from heaviercomponents (e.g., ethane, ethylene, propane, propylene and any otherless volatile component present in the OCM effluent stream 3005). Thelight components are directed to an overhead stream 3010 while theheavier components are directed along the bottom product stream 3009.The de-methanizer 3002 can be designed such that at least about 60%,70%, 80%, 90%, or 95% of the ethylene in the OCM effluent stream 3005 isdirected to the bottom product stream 3009.

The de-methanizer overhead stream 3010, which can contain at least 50%,60%, or 70% methane, can be divided into two streams. A first stream3011 is compressed in compressor 3012 and cooled in the second heatexchanger 3003 and phase separated in a phase separation unit 3013(e.g., vapor-liquid separator or distillation column). Vapors from thephase separation unit 3013 are expanded (e.g., in a turbo-expander orsimilar device) to provide part of the cooling duty required in heatexchangers 3001, 3003 and 3004. Liquids from the phase separation unit3013 are sub-cooled in the third heat exchanger 3004 and recycled to thede-methanizer 3002. A second stream 3014 from the overhead stream 3010can be expanded (e.g., in a turbo-expander or similar device) todecrease its temperature and provide additional cooling to the heatexchangers 3001, 3003 and 3004.

FIG. 31 shows another separation system 3100 that may be employed foruse with systems and methods of the present disclosure. The direction offluid flow is shown in the figure. The system 3100 comprises a firstheat exchanger 3101, a de-methanizer 3102, and a second heat exchanger3103. An OCM effluent stream 3104 is directed to the first heatexchanger 3101 at a pressure from about 2 bar (absolute) to 100 bar, or3 bar to 10 bar. The first heat exchanger 3101 can interface with apropane refrigeration unit 3115 and/or an ethylene refrigeration unit3116. In the first heat exchanger 3101, the OCM effluent stream 3104 canbe cooled upon heat transfer to de-methanizer overhead streams 3105 and3106, a de-methanizer reboiler stream, a de-methanizer pump-aroundstream, and various levels of external refrigeration, such as usingcooling fluids comprising ethylene and propylene. In some cases, thede-methanizer overhead streams 3105 and 3106 are combined into a singlestream 3114 before or after they are cooled. The cooled OCM effluentstream 3104 is then directed to the de-methanizer 3102, where lightcomponents (e.g., CH₄, H₂ and CO) are separated from heavier components(e.g., ethane, ethylene, propane, propylene and any other less volatilecomponent present in the OCM effluent stream 3104). The light componentsare directed to an overhead stream 3107 and the heavier components aredirected along a bottom product stream 3108. The de-methanizer 3102 canbe designed such that at least about 60%, 70%, 80%, 90%, or 95% of theethylene in the OCM effluent stream 3104 is directed to the bottomproduct stream 3108.

The de-methanizer overhead stream, which can contain at least about 50%,60%, or 70% methane, can be divided into two streams. A first stream3113 can be compressed in a compressor 3109, cooled in the second heatexchanger 3103 and phase-separated in a phase separation unit 3110(e.g., distillation column or vapor-liquid separator). Vapors from thephase separation unit 3110 can be expanded (e.g., in a turbo-expander orsimilar device) to provide part of the cooling duty required for theheat exchanger 3101 and 3103. Liquids from the phase separation unit3110 can be sub-cooled and flashed (e.g., over a valve or similardevice), and the resulting two-phase stream is separated in anadditional phase separation unit 3111. Liquids from the additional phaseseparation unit 3111 are recycled to the de-methanizer 3102 and vaporsfrom the additional phase separation unit are mixed with expanded vaporsfrom the phase separation unit 3110 prior to being directed to thesecond heat exchanger 3103.

A second stream 3112 from the overhead stream 3107 can be expanded(e.g., in a turbo-expander or similar device) to decrease itstemperature and provide additional cooling for the heat exchanger 3101and 3103. Any additional cooling that may be required for the secondheat exchanger 3103 can be provided by an external refrigeration system,which may employ a cooling fluid comprising ethylene or an equivalentcooling medium.

In some cases, recycle split vapor (RSV) separation can be performed incombination with de-methanization.

In some instances, the methane undergoes an OCM and/or ETL process toproduce liquid fuel or aromatic compounds (e.g., higher hydrocarbonliquids) and contains molecules that have gone through methanation. Insome embodiments, the compounds have been through a recycle split vapor(RSV) separation process. In some cases, alkanes (e.g., ethane, propane,butane) are cracked in a post-bed cracker.

Systems above and elsewhere herein are not limited to ethylene and maybe configured to operate with other olefins, such as propylene, butenes,pentene, or other alkenes. Although various systems and methods hereinhave been described in the context of ethylene to liquids, it will beappreciated that other alkenes may be used. For example, an OCM reactormay generate an OCM effluent stream comprising propylene and/or one ormore butenes, which may be used to provide one or more streamscomprising higher molecular weight hydrocarbons.

Systems of the present disclosure may be suitable for generating liquidsat less than or equal to about 250 kilotons per annum (KTA) (“smallscale”), or generating liquids at greater than about 250 KTA (“worldscale”). In some examples, a world scale OCM-ETL system generates atleast about 1000, 1100, 1200, 1300, 1400, 1500, or 1600 KTA of liquids.

Ethane Skimmers

The systems and methods described herein can process natural gas intogas that is suitable for sale (i.e., “sales gas” that meets thespecifications required for transportation by pipeline). In some cases,the systems and methods of the present disclosure can convert methaneand/or ethane (e.g., from natural gas) to sales gas as well as productssuch as LPG, gasoline, distillate fuels, and/or aromatic chemicals. Sucha system or method is referred to as an “ethane skimmer”.

Ethane can be fed directly into a post-bed cracker (PBC), which can be aportion of an OCM reactor downstream of the OCM catalyst, where the heatgenerated in the OCM reaction can be used to crack the ethane toethylene. As an alternative, the PBC can be a unit that is separate fromthe OCM reactor and in some cases in thermal communication with the OCMreactor. The ethane feed stream to the OCM reactor can include (a)ethane recycled to the OCM reactor from an OCM reactor effluent stream,which can be separated in at least one downstream separation module andrecycled to the OCM reactor, (b) ethane present in other feed streams(e.g., natural gas), which can be separated in at least one separationmodule and recycled to the OCM reactor, and (c) any additional (i.e.,fresh) ethane feed.

The maximum amount of ethane that can be converted in the PBC can belimited by the flow rate of material exiting the OCM catalyst and/or itstemperature. It can be advantageous to utilize a high proportion of themaximum amount of PBC. In some cases, the amount of ethane converted toethylene is about 50%, about 60%, about 70%, about 80%, about 85%, about90%, about 95%, or about 99% of the maximum amount of ethane that can beconverted to ethylene in the PBC. In some instances, the amount ofethane converted to ethylene is at least about 50%, at least about 60%,at least about 70%, at least about 80%, at least about 85%, at leastabout 90%, at least about 95%, or at least about 99% of the maximumamount of ethane that can be converted to ethylene in the PBC.

Achieving a high proportion of the maximum PBC capacity can beaccomplished by adding natural gas to the system, which can have aconcentration of ethane that depends on many factors, including thegeography and type and age of the natural gas well. The treatment andseparation modules of the process described herein can be used to purifyor fractionate the ETL effluent, and can additionally be used to treat(e.g., remove water and CO₂) and purify the natural gas that is added tothe system along with the ETL effluent, such as, e.g., by separating C₂₊compounds from methane and separating ethane from ethylene. In somecases, ethane contained in the natural gas feed can be recycled to theOCM reactor (e.g., PBC region) as pure ethane and the system may not besensitive to the purity and composition of the natural gas, making rawnatural gas a suitable input to the system.

The maximal PBC capacity can depend on the ratio between methane andethane in the input to the OCM reactor, including in some instances thePBC portion. In some cases, the PBC capacity is saturated when the molarratio of methane to ethane is about 1, about 2, about 3, about 4, about5, about 6, about 7, about 8, about 9, about 10, about 11, about 12,about 13, about 14, or about 15. In some cases, the PBC capacity issaturated when the molar ratio of methane to ethane is at least about 1,at least about 2, at least about 3, at least about 4, at least about 5,at least about 6, at least about 7, at least about 8, at least about 9,at least about 10, at least about 11, at least about 12, at least about13, at least about 14, or at least about 15. In some cases, the PBCcapacity is saturated when the molar ratio of methane to ethane is atmost about 5, at most about 6, at most about 7, at most about 8, at mostabout 9, at most about 10, at most about 11, at most about 12, at mostabout 13, at most about 14 or at most about 15. In some cases, the PBCcapacity is saturated when the molar ratio of methane to ethane isbetween about 7 and 10 parts methane to one part ethane.

Natural gas (raw gas or sales gas) can have a concentration of ethane ofless than about 30 mol %, 25 mol %, 20 mol %, 15 mol %, 10 mol %, 9 mol%, 8 mol %, 7 mol %, 6 mol %, 5 mol %, 4 mol %, 3 mol %, 2 mol % or 1mol %. In some cases, natural gas has a methane to ethane ratio greaterthan about 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1,12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, 20:1 or 40:1. The ethaneskimmer implementation described herein can be used to inject morenatural gas feed into the system than what may be required to producethe desired or predetermined amount of ethylene or other products. Theexcess methane can be drawn from a stream downstream of the methanationunit and sold as sales gas (which may lack an appreciable amount ofethane but can still meet pipeline specifications and/or can be directedto a power plant for power production). The ethane in the additionalnatural gas feed can be used to saturate the PBC capacity. Any excessethane can be drawn from the C₂ splitter and exported as pure ethane.The ethane skimmer implementation described herein can result inadditional product streams from the system (namely sales gas, naturalgas liquids, gasoline, diesel or jet fuels and/or aromatic chemicals).In such a case, the process can be used to achieve both natural gasprocessing and production of C₂₊ chemicals or fuels.

The ethane skimmer implementation can be readily understood by referenceto FIG. 32. Natural gas 3200 can be fed into a desulfurization unit 3202and then into a gas compressor 3204. Oxygen can be provided from an airseparation unit 3206 that can be powered by a gas turbine andcombination cycle 3208 that is powered by combustion of a portion of thenatural gas and/or methane. The oxygen and methane 3210 produced by theprocess can be injected into an OCM reactor 3212 having a PBC portion3214. The OCM effluent can be fed into the process gas compressor 3204and then into the ETL module 3216. Products of the ETL module can bedried in a drier 3218. The separation module can comprise ade-methanizer 3220, a de-ethanizer 3222 and a de-butanizer 3224. Thede-methanizer can separate C₁ compounds from C₂₊ compounds and directthe C₁ compounds (e.g., methane, carbon monoxide and carbon dioxide) toa methanator 3226. The C₁ compound stream can have any amount of C₂₊compounds (e.g., about 0.5%, about 1%, about 1.5%, about 2%, about 2.5%,about 3%, or about 3.5%). The methanator can convert the carbon monoxideand/or carbon dioxide to methane (e.g., using hydrogen generated in theprocess). The methane can be divided into any number of streams that canbe directed to the OCM reactor 3212, the gas turbine 3208, and/or apipeline 3228 or other means for delivering a methane product to themarket (i.e., sales gas). The ethane 3230 from the separation module canbe directed to the PBC. The system can produce C₃₊ products such asliquified petroleum gas (LPG; having C₃ and C₄ molecules) 3232 and C₅₊products 3234 such as gasoline, diesel fuel, jet fuel, and/or aromaticchemicals.

Overall, in the ethane skimmer process as shown in FIG. 32, at leastsome or most (e.g., >70%, >80%, >85%, >90%, >95%, or >99%) of themethane in the natural gas feed 3200 ends up in the methane recycle3210, at least some or most (e.g., >70%, >80%, >85%, >90%, >95%,or >99%) of the ethane in the natural gas feed ends up in the ethanerecycle stream 3230, at least some or most(e.g., >70%, >80%, >85%, >90%, >95%, or >99%) propane in the natural gasfeed ends up in the C₃₊ products streams 3232 and 3234. In some cases,and ethane is added (not shown in FIG. 32) up to the point where the PBCcracking capacity is saturated or nearly saturated(e.g., >70%, >80%, >85%, >90%, >95%, or >99%). Excess ethane (e.g.,beyond what is needed to saturate the PBC) can end up in an ethaneproduct stream (not shown). The ethane skimmer implementation does notrequire a separate (i.e., fresh) ethane stream to saturate or nearlysaturate the PBC capacity of the system.

Additional Products and Processes

In addition to the ethylene conversion processes described herein,components other than ethylene that are produced in an ethyleneproduction process, e.g., contained within an OCM effluent gas, may bedirected to, and thus fluidly connected to additional conversionprocesses. In particular, the OCM reaction process generates a number ofadditional products, other than ethylene, including for example,hydrogen gas (H₂) and carbon monoxide (CO). In some cases, the H₂ and COcomponents of the OCM reaction product slate are subjected to additionalprocessing to produce other products and intermediates, e.g.,dimethylether (DME), methanol, and hydrocarbons. These components may beuseful in a variety of different end products, including liquid fuels,lubricants and propellants. In some embodiments, the H₂ and COcomponents of the OCM reaction effluent are separated from the other OCMproducts. The H₂ and CO can then be subjected to any of a variety ofsyngas-like conversion processes to produce a variety of differentproducts, e.g., methanol, dimethylether, hydrocarbons, lubricants, waxesand fuels or fuel blendstocks. In one example, the H₂ and CO componentsare subjected to a catalytic process to produce DME via a methanolintermediate. The catalytic process is described in detail in, e.g.,U.S. Pat. No. 4,481,305, the full disclosure of which is incorporatedherein by reference in its entirety for all purposes.

As noted herein, the ethylene conversion processes employed in theintegrated processes and systems of the invention may produce olefinicproducts for use in a variety of different end products or applications.For example, a portion or all of the ethylene produced by the OCMprocess may be routed through one or more catalytic processes or systemsto oligomerize ethylene into LAOs of ranging carbon numbers. Thesecompounds can be particularly useful in chemical manufacturing, e.g., inthe production of amines, amine oxides, oxo-alcohols, alkylatedaromatics epoxides, tanning oils, synthetic lubricants, lubricantadditives, alpha olefin sulfonates, mercaptans, organic alkyl aluminum,hydrogenated oligomers, and synthetic fatty acids. Alternatively oradditionally, the ethylene may be oligomerized through LAO processes toproduce C₄-C₂₀ LAOs for use as liquid blend stocks for gasoline, dieselor jet fuels. These LAOs can also be hydrogenated to linear alkanes forfuel blend stocks for gasoline, jet, and diesel fuel.

Processes used for the production of product ranges, e.g., C₄-C₃₀ LAOs,are generally referred to herein as “full range processes” or “narrowrange processes”, as they produce a range of chemical species, e.g.,LAOs of varying chain length such as 1-butene, 1-hexene, 1-octene,1-decene, etc., in a single process. Products from full range or narrowrange processes may be distilled or fractionated into, e.g., C₄-C₁₀ LAOsfor use as chemical process feedstocks, C₁₀-C₂₀ LAOs for use as a jetfuel blendstock, diesel fuel blendstock, and chemical feedstock. Bycontrast, processes that produce a single product species in high yield,e.g., LAO of a single chain length such as 1-butene, 1-hexene, 1-octene,1-decene or the like, are referred to generally as selective processes.

Full and narrow ranges of products may be prepared from ethylene using avariety of LAO processes, such as, for example, the α-Sablin® process(See, e.g., Published International Patent Application No. WO2009/074203, European Patent No. EP 1749806B1, and U.S. Pat. No.8,269,055, the full disclosures of which are incorporated herein byreference in their entirety for all purposes), the Shell higher olefinprocess (SHOP), the Alphabutol process, the Alphahexol process, theAlphaSelect process, the Alpha-Octol process, Linear-1 process, theLinealene process, the Ethyl Process, the Gulftene process, and thePhillips 1-hexene process.

Briefly, the α-Sablin process employs a two-component catalyst system ofa zirconium salt and an aluminum alkyl co-catalyst, for homogenous,liquid phase oligomerization of ethylene to a narrow range of LAOs. Thecatalytic cycle comprises a chain growth step by an ethylene insertionreaction at the co-ordination site and displacement of the coordinatedhydrocarbon from the organometallic complex. The ratio of zirconium toaluminum can be used to adjust between chain growth and displacement,thereby adjusting the product spectrum more toward lighter or heavierLAOs. For example, with a high Zr:Al ratio, the product spectrum can beshifted to upwards of 80% C4-C8 LAOs, while lower Zr:Al ratios willshift the product spectrum towards heavier LAOs. The reaction isgenerally carried out in a bubble column reactor with a solvent, such astoluene, and catalyst being fed into the liquid phase at temperatures ofbetween about 60° C. and 100° C. and pressures of between about 20 barand 30 bar. The liquid LAOs are then sent to a separation train todeactivate the catalyst, separate the solvent and optionally perform anyadditional product separations that are desired.

Additionally, all or a portion of these olefinic products may behydrogenated prior to distillation to convert the olefins into thecorresponding alkanes for use as alkane blendstocks for fuel products,and then again, subjected to a distillation or other separation processto produce the desired products.

In various embodiments, a wide range of other ethylene conversionprocesses may be integrated at the back end of the OCM processesdescribed above, depending upon the desired product or products for theoverall process and system. For example, in alternative or additionalaspects, an integrated ethylene conversion process for production ofLAOs may include the SHOP system, a full range ethylene conversionprocess which may be used to produce LAOs in the C₆-C₁₆ range. Briefly,the SHOP system employs a nickel-phosphine complex catalyst tooligomerize ethylene at temperatures of from about 80° C. to about 120°C., and pressures of from about 70 bar to about 140 bar.

A variety of other full-range ethylene conversion processes may beemployed, including without limitation, the AlphaSelect process, theAlpha-Octol process, Linear-1 process, the Linealene process, theSynthol process, the Ethyl Process, the Gulftene process, the Phillips1-hexene process, and others. These processes are well characterized inthe literature, and reported, for example at the Nexant/Chemsystems PERPreport, Alpha Olefins, January 2004, the full disclosure of which areincorporated herein by reference in their entirety for all purposes.

As an alternative or in addition to full and/or narrow range ethyleneconversion processes, ethylene conversion processes that may beintegrated into the overall systems of the invention include processesfor the selective production of high purity single compound LAOcompositions. As used herein, processes that are highly selective forthe production of a single chemical species are generally referred to asselective or “on purpose” processes, as they are directed at productionof a single chemical species in high selectivity. In the context of LAOproduction, such on purpose processes will typically produce a singleLAO species, e.g., 1-butene, 1-hexene, 1-octene, etc., at selectivitiesof greater than 50%, in some cases greater than 60%, greater than 75%,and even greater than 90% selectivity for the single LAO species.

Examples of such on purpose processes for ethylene conversion to LAOsinclude, for example, the Alphahexol process from IFP, the Alphabutolprocess, or the Phillips 1-hexene process for the oligomerization ofethylene to high purity 1-hexene, as well as a wide range of otherprocesses that may be integrated with the overall OCM reactor system.

The Alphahexol process, for example, is carried out using phenoxideligand processes. In particular, ethylene trimerization may be carriedout using a catalytic system that involves a chromium precursor, aphenoxyaluminum compound or alkaline earth phenoxide and atrialkylaluminum activator at 120° C. and 50 bar ethylene pressure (See,e.g., U.S. Pat. No. 6,031,145, and European Patent No. EP1110930, thefull disclosures of which are incorporated herein by reference in theirentirety for all purposes). Likewise, the Phillips 1-hexene processemploys a chromium(III) alkanoate, such as chromiumtris(2-ethylhexanoate, pyrrole, such as 2,5-dimethylpyrrole, and Et3Alto produce 1-hexene at high selectivity, e.g., in excess of 93%. See,e.g., European Patent No. EP0608447 and U.S. Pat. No. 5,856,257, thefull disclosures of which are incorporated herein by reference in theirentirety for all purposes. A variety of other ethylene trimerizationprocesses may be similarly integrated to the back end of the OCM systemsdescribed herein. These include, for example, the British Petroleum PNPtrimerization system (see, e.g., Published International PatentApplication No. WO 2002/04119, and Carter et al., Chem. Commun. 2002,858), and Sasol PNP trimerization system (see, e.g., PublishedInternational Patent Application No. WO2004/056479, discussed in greaterdetail), the full disclosures of which are incorporated herein byreference in their entirety for all purposes.

The Alphabutol process employs a liquid phase proprietary solublecatalyst system of Ti(IV)/AlEt3, in the dimerization of ethylene to1-butene at relatively high purity, and is licensed through Axens(Rueil-Malmaison, France). Ethylene is fed to a continuous liquid phasedimerization reactor. A pump-around system removes the exothermic heatof reaction from the reactor. The reactor operates between 50-60° C. at300-400 psia. The catalyst is removed from the product effluent and isultimately fed to the 1-butene purification column where comonomer-grade1-butene is produced.

Still other selective ethylene conversion processes include thecatalytic tetramerization of ethylene to 1-octene. For example, oneexemplary tetramerization process employs a liquid phase catalyticsystem using a Cr(III) precursor, such as [Cr(acac)₃] or [CrCl3(THF)3]in conjunction with a bis(phosphine)amine ligand and amethylaluminooxane (MAO) activator at temperatures of between about 40°C. and 80° C. and ethylene pressures of from 20 to 100 bar, to produce1-octene with high selectivity. See, e.g., Published InternationalPatent Application No. WO2004/056479 and Bollmann, et al., “EthyleneTetramerization: A New Route to Produce 1-Octene in Exceptionally HighSelectivities” J. Am. Chem. Soc., 2004, 126 (45), pp 14712-14713, thefull disclosures of which are incorporated herein by reference in theirentirety for all purposes.

In addition to the LAO processes described herein, ethylene producedfrom the integrated OCM reactor systems can also be used to makeolefinic non-LAO linear hydrocarbons and branched olefinic hydrocarbonsthrough the same or different integrated processes and systems. Forexample, the ethylene product from the OCM reactor system may be passedthrough integrated reactor systems configured to carry out the SHOPprocess, the Alphabutol process, the Alphahexol process, the AlphaSelectprocess, the Alpha-Octol process, Linear-1 process, the Linealeneprocess, the Ethyl Process, the Gulftene process, and/or the Phillips1-hexene process, to yield the resultant LAO products. The output ofthese systems and processes may then be subjected to an olefinisomerization step to yield linear olefins other than LAOs, branchedolefinic hydrocarbons, or the like. In addition, olefinic non-LAO linearhydrocarbons and branched olefinic hydrocarbons can be prepared byethylene oligomerization over heterogeneous catalysts such as zeolites,amorphous silica/alumina, solid phosphoric acid catalysts, as well asdoped versions of the foregoing catalysts.

Other oligomerization processes have been described in the art,including the olefin oligomerization processes set forth in PublishedU.S. Patent Application No. 2012/0197053 (incorporated herein byreference in its entirety for all purposes), which describes processesused for production of liquid fuel components from olefinic materials.

Although a number of processes are described with certain specificity,that description is by way of example and not limitation. In particular,it is envisioned that the full range of ethylene oligomerization and/orconversion processes may be readily integrated onto the back end of theOCM reactor systems for conversion of methane to ethylene product, andsubsequently to a wide range of different higher hydrocarbon products.As noted previously, certain embodiments of the ethylene conversionprocesses that are integrated into the overall systems of the inventionare those that yield liquid hydrocarbon products. Other embodiments ofthe ethylene conversion processes that are integrated in the overallsystems include process that are particularly well-suited for use withdilute ethylene feed stocks which optionally comprise additionalcomponents such as higher hydrocarbons, unreacted OCM starting material(methane and/or other natural gas components) and/or side products ofthe OCM reactions. Examples of such other components are providedherein.

In addition to or as an alternative, the ethylene product produced fromthe OCM reactor system may be routed through one or more catalytic orother systems and processes to make non-olefinic hydrocarbon products.For example, saturated linear and branched hydrocarbon products may beproduced from the ethylene product of the OCM reactor system through thehydrogenation of the products of the olefinic processes described above,e.g., the SHOP process, the Alphabutol process, the Alphahexol process,the AlphaSelect process, the Alpha-Octol process, Linear-1 process, theLinealene process, the Ethyl Process, the Gulftene process, and/or thePhillips 1-hexene process.

Other catalytic ethylene conversions systems that may be employedinclude reacting ethylene over heterogeneous catalysts, such aszeolites, amorphous silica/alumina, solid phosphoric acid catalysts,and/or doped forms of these catalysts, to produce mixtures ofhydrocarbons, such as saturated linear and/or branched hydrocarbons,saturated olefinic cyclic hydrocarbons, and/or hydrocarbon aromatics. Byvarying the catalysts and or the process conditions, selectivity of theprocesses for specific components may be enhanced. For example, ethylenepurified from OCM effluent or unpurified OCM effluent containingethylene can be flowed across a zeolite catalyst, such as ZSM-5, oramorphous silica/alumina material with SiO₂/Al₂O₃ ratios of 23-280, atethylene partial pressures between 0.01 bar to 100 bar (undoped, ordoped with Zn and/or Ga in some embodiments or some combination thereof)at temperatures above 350° C. to give high liquid hydrocarbon yield(80+%) and high aromatic selectivity (benzene, toluene, xylene (BTX)selectivity >90% within the liquid hydrocarbon fraction). Ethylenepurified from OCM effluent or unpurified OCM effluent containingethylene can be flowed across a zeolite catalyst, such as ZSM-5, oramorphous silica/alumina material with SiO₂/Al₂O₃ ratios of 23-280, atethylene partial pressures between 0.01 bar to 100 bar (undoped, or withdopants including but not limited to, e.g., Ni, Mg, Mn, Ca, and Co, orsome combination of these) at temperatures above 200° C., to give highliquid hydrocarbon yield (80+%) and high gasoline selectivity (gasolineselectivity >90% within the liquid hydrocarbon fraction). Ethylenepurified from OCM effluent or unpurified OCM effluent containingethylene can be flowed across a zeolite catalyst, such as ZSM-5, oramorphous silica/alumina material with SiO₂/Al₂O₃ ratios of 23-280 or asolid phosphoric acid catalyst, at ethylene partial pressures between0.01 bar to 100 bar at temperatures above 200° C. to give high liquidhydrocarbon yield (80+%) and high distillate selectivity (gasolineselectivity >90% within the liquid hydrocarbon fraction).

In some embodiments, to achieve high jet/diesel fuel yields, a twooligomerization reactor system is used in series. The firstoligomerization reactor takes the ethylene and oligomerizes it to C₃-C₆olefins over modified ZSM-5 catalysts, e.g., Mg, Ca, or Sr doped ZSM-5catalysts. The C₃-C₆ olefins can be the end products of the process oralternatively can be placed in a second oligomerization reactor to becoupled into jet/diesel fuel range liquid.

In addition, some embodiments of the ethylene conversion processes alsoinclude processes for production of oxygenated hydrocarbons, such asalcohols and/or epoxides. For example, the ethylene product can berouted through an integrated system that includes a heterogeneouscatalyst system, such as a solid phosphoric acid catalyst in thepresence of water, to convert the ethylene to ethanol. This process hasbeen routinely used to produce 200 proof ethanol in the process used byLyondellBasell. In other embodiments, longer chain olefins and/or LAO's,derived from OCM ethylene by oligomerization, can be likewise convertedto alkyl alcohols using this same process. See, e.g., U.S. Pat. Nos.2,486,980; 3,459,678; 4,012,452, the full disclosures of which areincorporated herein by reference in their entirety for all purposes. Inalternate embodiments, ethylene undergoes a vapor oxidation reaction tomake ethylene oxide over a silver based catalyst at 200-300° C. at 10-30atmospheres of pressure with high selectivity (80+%). Ethylene oxide isan important precursor for synthesis of ethylene glycol, polyethyleneglycol, ethylene carbonate, ethanolamines, and halohydrins. See, e.g.,Chemsystems PERP Report Ethylene Oxide/Ethylene Glycol 2005, which isherein incorporated by reference.

In still other aspects, the ethylene product produced from the OCMreactor system may be routed to a reactor system that reacts theethylene with various halogen sources (acids, gases, and others) to makehalogenated hydrocarbons useful, for example, as monomers in producinghalogenated polymers, such as polyvinyl chloride (PVC). For example, inone ethylene dichloride (EDC) process, available from ThyssenKrupp Uhde,ethylene can be reacted with chlorine gas to make EDC, an importantprecursor to vinyl-chloride monomer (VCM) for polyvinylchloride (PVC)production. This process also can be modified EDC to react ethylene withhydrochloric acid (HCl) to make EDC via oxychlorination.

In still other exemplary ethylene conversion processes, the ethyleneproduct of the OCM reactor system may be converted to alkylated aromatichydrocarbons, which are also useful as chemical and fuel feedstocks. Forexample, in the Lummus CD-Tech EB process and the Badger EB process,benzene can be reacted with OCM ethylene, in the presence of a catalyst,to make ethylbenzene. See, e.g., U.S. Pat. No. 4,107,224, the fulldisclosure of which is incorporated herein by reference in its entiretyfor all purposes. Ethylbenzene can be added to gasoline as a high-octanegasoline blendstock or can be dehydrogenated to make styrene, theprecursor to polystyrene.

In addition to the liquid and other hydrocarbons described above, incertain aspects, one or more of the integrated ethylene conversionprocesses is used to convert ethylene product from the OCM reactorsystem to one or more hydrocarbon polymers or polymer precursors. Forexample, in some embodiments ethylene product from the integrated OCMreactor systems is routed through an integrated Innovene process system,available through Ineos Technologies, Inc., where the ethylene ispolymerized in the presence of a catalyst, in either a slurry or gasphase system, to make long hydrocarbon chains or polyethylene. Byvarying the process conditions and catalyst the process and system canbe used to produce high density polyethylene or branched low densitypolyethylene, etc. The Innovene G and Innovene S processes are describedat, for example, at “Ineostechnologies.com”. See also Nexant/ChemsystemsHDPE Report, PERP 09/10-3, January 2011, the full disclosure of which isincorporated herein by reference in its entirety for all purposes.

Alternatively, ethylene from OCM can be introduced, under high pressure,into an autoclave or tubular reactor in the presence of a free radicalinitiator, such as O₂ or peroxides, to initiate polymerization for thepreparation of low-density polyethylene (LDPE). See e.g., “AdvancedPolyethylene Technologies” Adv Polym Sci (2004) 169:13-27, the fulldisclosure of which is incorporated herein by reference in its entiretyfor all purposes. Alternatively, ethylene from OCM can be introduced,under low pressure in the presence of a chromium oxide based catalyst,Ziegler-Natta catalyst, or a single-site (metallocene or non metallocenebased) catalyst, to prepare HDPE, MDPE, LLDPE, mLLDPE, or bimodalpolyethylene. The reactor configurations for synthesis of HDPE, LLDPE,MDPE, and biomodal PE can be a slurry process, in which ethylene ispolymerized to form solid polymer particles suspended in a hydrocarbondiluent, a solution process in which dissolved ethylene is polymerizedto form a polymer dissolved in solvent, and/or a gas phase process inwhich ethylene is polymerized to form a solid polymer in a fluidized bedof polymer particles. Ethylene from OCM can be co-polymerized withdifferent monomers to prepare random and block co-polymers. Co-monomersfor ethylene copolymerization include but are not limited to: at leastone olefin comonomer having three to fifteen carbons per molecule(examples are propylene and LAO's such as 1-butene, 1-hexene, 1-octene),oxygenated co-monomers such as: carbon oxide; vinyl acetate, methylacrylate; vinyl alcohols; allyl ethers; cyclic monomers such asnorbornene and derivatives thereof, aromatic olefins such as: styreneand derivatives thereof. These ethylene or LAO copolymerizationprocesses, e.g., where ethylene is copolymerized with differentmonomers, are generally referred to herein as copolymerization processesor systems.

More exemplary ethylene conversion processes that may be integrated withthe OCM reactor systems include processes and systems for carrying outolefin metathesis reactions, also known as disproportionation, in theproduction of propylene. Olefin metathesis is a reversible reactionbetween ethylene and butenes in which double bonds are broken and thenreformed to form propylene. “Propylene Production via Metathesis,Technology Economics Program” by Intratec, ISBN 978-0-615-61145-7, Q22012, the full disclosure of which is incorporated herein by referencein its entirety for all purposes. Propylene yields of about 90 wt % areachieved. This option may also be used when there is no butenefeedstock. In this case, part of the ethylene from the OCM reactionfeeds into an ethylene-dimerization unit that converts ethylene intobutene.

As noted herein, one, two, three, four or more different ethyleneconversion processes are provided integrated into the overall systems ofthe invention, e.g., as shown in FIG. 1. As will be appreciated, theseethylene conversion systems will include fluid communications with theOCM systems described herein, and may be within the same facility orwithin an adjacent facility. Further, these fluid communications may beselective. In particular, in certain embodiments the interconnectbetween the OCM system component and the ethylene conversion systemcomponent(s) is able to selectively direct all of an ethylene productfrom the OCM system to any one ethylene conversion system at a giventime, and then direct all of the ethylene product to a second differentethylene conversion system component at a different time. Alternatively,such selective fluid communications may also simultaneously directportions of the ethylene product to two or more different ethyleneconversion systems to which the OCM system is fluidly connected.

These fluid communications will typically comprise interconnected pipingand manifolds with associated valving, pumps, thermal controls and thelike, for the selective direction of the ethylene product of the OCMsystem to the appropriate ethylene conversion system component orcomponents.

In an example, ethylene produced by the methods described herein (e.g.,by OCM) can be converted into 1-butene or 2-butene. In some cases, ETLmethods and systems provided herein can be used to form 1-butene but noappreciable 2-butene, or 2-butene but no appreciable 1-butene. Methodsfor generating 1-butene from ethylene are disclosed in U.S. Pat. Nos.2,943,125, 3,686,350, 4,101,600, 8,624,042, and 5,792,895, each of whichis entirely incorporated herein by reference.

As an alternative or in addition to, ethylene produced by the methodsdescribed herein (e.g., by OCM) can be converted into 1-hexene. Methodsfor converting ethylene to 1-hexene are described in U.S. Pat. Nos.6,380,451, 7,157,612, 5,057,638, 8,658,750, and 5,811,618, each of whichis entirely incorporated herein by reference. As an alternative or inaddition to, ethylene produced by the methods described herein (e.g., byOCM) can be converted into 1-octene. Methods for converting ethylene to1-Octene are described in U.S. Pat. Nos. 5,292,979, 5,811,619,5,817,905, and 6,103,654, each of which is entirely incorporated hereinby reference.

In some cases, ethylene produced by the methods described herein (e.g.,by OCM) can be converted into C4 to C18 and higher α-olefins (1-butene,1-hexene, 1-octene, 1-decene and higher). Oligomerization of ethyleneinto linear alpha olefins (LAO) can be carried out in a bubble columnreactor with the solvent and the dissolved catalyst components fed tothe liquid phase. Methods for converting ethylene to C₄-C₁₈ and higherα-olefins are described in Canadian Patent Application Number CA2,765,769, German Patent Number DE 4338414, German Patent Number DE4338416, U.S. Pat. Nos. 3,862,257, 4,966,874, and 5,449,850, each ofwhich is entirely incorporated herein by reference.

As an alternative or in addition to, ethylene produced by the methodsdescribed herein (e.g., by OCM) can be converted into C₄ to C₁₀α-olefins (1-butene, 1-hexene, 1-octene, and 1-decene). Methods forconverting ethylene to C₄-C₁₀ α-olefins are described in U.S. Pat. Nos.3,660,519, 3,584,071, European Patent Number EP 0,722,922, U.S. Pat.Nos. 4,314,090, 5,345,023, and 6,221,986, each of which is entirelyincorporated herein by reference.

In another example, ethylene produced by the methods described herein(e.g., by OCM) can be converted into propylene (propene). For example,n-butenes can be reacted with ethylene using a heterogeneous catalystsystem in a fixed bed reactor process. Methods for converting ethyleneto propylene are described in U.S. Pat. Nos. 6,683,019, 7,214,841,8,153,851, and 8,258,358, each of which is entirely incorporated hereinby reference.

As an alternative or in addition to, ethylene produced by the methodsdescribed herein (e.g., by OCM) can be converted into ethylenedichloride (EDC). For example, ethylene can be reacted with chlorine inliquid phase in presence of a catalyst system. Methods for convertingethylene to EDC are described in German Patent Number DE 19 05 517,German Patent Number DE 25 40 257, German Patent Number DE 40 39 960A16, U.S. Pat. Nos. 7,579,509, 7,671,244, and 6,841,708, each of whichis entirely incorporated herein by reference.

Ethylene produced by the methods described herein (e.g., by OCM) can beconverted into high density polyethylene (HDPE) or other types ofpolyethylene. For example, ethylene or a mixture of ethylene with one ormore alpha olefins can be reacted in the gas phase in the presence of acatalyst system. Methods for converting ethylene to HDPE are describedin U.S. Pat. Nos. 5,473,027, 5,473,027, 6,891,001, and 4,882,400, eachof which is entirely incorporated herein by reference.

The ethylene produced by the methods described herein (e.g., by OCM) canbe converted into ethanol. For example, a mixture of ethylene and wateris reacted over a heterogeneous catalyst (e.g., solid phosphoric acidcatalyst) in a reactor to form ethanol by direct hydration of ethylene.Methods for converting ethylene to ethanol are described in U.S. Pat.Nos. 2,486,980, 2,579,601, 2,673,221, and 3,686,334, each of which isentirely incorporated herein by reference.

Acetylene can be selectively hydrogenated to ethylene while present in amixture containing ethylene and other components without hydrogenatingethylene. For example, a feed containing acetylene and ethylene isreacted in the presence of hydrogen over a heterogeneous catalyst in afixed bed reactor system. Methods for selective hydrogenating acetyleneare described in U.S. Pat. Nos. 3,128,317, 4,126,645, 4,367,353,4,329,530, 4,440,956, 5,414,170, 6,509,292, and Xu, Ling, et al.“Maximise ethylene gain and acetylene selective hydrogenationefficiency,” Petroleum technology quarterly 18.3 (2013): 39-42, each ofwhich is entirely incorporated herein by reference.

Acetylene and dienes, such as butadiene, can be selectively hydrogenatedwhile present in a mixture containing ethylene and other componentswithout hydrogenating the ethylene present. For example, a feedcontaining acetylene and dienes is reacted in the presence of hydrogenover a heterogeneous catalyst in a fixed bed reactor system. Methods forselective hydrogenating acetylene and dienes are described in U.S. Pat.Nos. 3,900,526, 5,679,241, 6,759,562, 5,877,363, 7,838,710, and8,227,650, each of which is entirely incorporated herein by reference.

Olefin to Liquids Reactors Control Systems

The present disclosure provides computer control systems that can beemployed to regulate or otherwise control the methods and systemsprovided herein. A control system of the present disclosure can beprogrammed to control process parameters to, for example, effect a givenproduct distribution, such as a higher concentration of alkenes ascompared to alkanes in a product stream out of an OCM and/or ETLreactor.

FIG. 33 shows a computer system 3301 that is programmed or otherwiseconfigured to regulate OCM and/or ETL reactions, such as regulate fluidproperties (e.g., temperature, pressure and stream flow rate(s)),mixing, heat exchange and OCM and/or ETL reactions. The computer system3301 can regulate, for example, fluid stream (“stream”) flow rates,stream temperatures, stream pressures, OCM and/or ETL reactortemperature, OCM and/or ETL reactor pressure, the quantity of productsthat are recycled, and the quantity of a first stream (e.g., methanestream) that is mixed with a second stream (e.g., air stream).

The computer system 3301 includes a central processing unit (CPU, also“processor” and “computer processor” herein) 3305, which can be a singlecore or multi core processor, or a plurality of processors for parallelprocessing. The computer system 3301 also includes memory or memorylocation 3310 (e.g., random-access memory, read-only memory, flashmemory), electronic storage unit 3315 (e.g., hard disk), communicationinterface 3320 (e.g., network adapter) for communicating with one ormore other systems, and peripheral devices 3325, such as cache, othermemory, data storage and/or electronic display adapters. The memory3310, storage unit 3315, interface 3320 and peripheral devices 3325 arein communication with the CPU 3305 through a communication bus (solidlines), such as a motherboard. The storage unit 3315 can be a datastorage unit (or data repository) for storing data.

The CPU 3305 can execute a sequence of machine-readable instructions,which can be embodied in a program or software. The instructions may bestored in a memory location, such as the memory 3310. Examples ofoperations performed by the CPU 3305 can include fetch, decode, execute,and writeback.

The storage unit 3315 can store files, such as drivers, libraries andsaved programs. The storage unit 3315 can store programs generated byusers and recorded sessions, as well as output(s) associated with theprograms. The storage unit 3315 can store user data, e.g., userpreferences and user programs. The computer system 3301 in some casescan include one or more additional data storage units that are externalto the computer system 3301, such as located on a remote server that isin communication with the computer system 3301 through an intranet orthe Internet.

The computer system 3301 can be in communication with an OCM and/or ETLsystem 3330, including an OCM and/or ETL reactor and various processelements. Such process elements can include sensors, flow regulators(e.g., valves), and pumping systems that are configured to direct afluid.

Methods as described herein can be implemented by way of machine (e.g.,computer processor) executable code stored on an electronic storagelocation of the computer system 3301, such as, for example, on thememory 3310 or electronic storage unit 3315. The machine executable ormachine readable code can be provided in the form of software. Duringuse, the code can be executed by the processor 3305. In some cases, thecode can be retrieved from the storage unit 3315 and stored on thememory 3310 for ready access by the processor 3305. In some situations,the electronic storage unit 3315 can be precluded, andmachine-executable instructions are stored on memory 3310.

The code can be pre-compiled and configured for use with a machine havea processor adapted to execute the code, or can be compiled duringruntime. The code can be supplied in a programming language that can beselected to enable the code to execute in a pre-compiled or as-compiledfashion.

Aspects of the systems and methods provided herein, such as the computersystem 3301, can be embodied in programming. Various aspects of thetechnology may be thought of as “products” or “articles of manufacture”typically in the form of machine (or processor) executable code and/orassociated data that is carried on or embodied in a type of machinereadable medium. Machine-executable code can be stored on an electronicstorage unit, such memory (e.g., read-only memory, random-access memory,flash memory) or a hard disk. “Storage” type media can include any orall of the tangible memory of the computers, processors or the like, orassociated modules thereof, such as various semiconductor memories, tapedrives, disk drives and the like, which may provide non-transitorystorage at any time for the software programming. All or portions of thesoftware may at times be communicated through the Internet or variousother telecommunication networks. Such communications, for example, mayenable loading of the software from one computer or processor intoanother, for example, from a management server or host computer into thecomputer platform of an application server. Thus, another type of mediathat may bear the software elements includes optical, electrical andelectromagnetic waves, such as used across physical interfaces betweenlocal devices, through wired and optical landline networks and overvarious air-links. The physical elements that carry such waves, such aswired or wireless links, optical links or the like, also may beconsidered as media bearing the software. As used herein, unlessrestricted to non-transitory, tangible “storage” media, terms such ascomputer or machine “readable medium” refer to any medium thatparticipates in providing instructions to a processor for execution.

Hence, a machine readable medium, such as computer-executable code, maytake many forms, including but not limited to, a tangible storagemedium, a carrier wave medium or physical transmission medium.Non-volatile storage media include, for example, optical or magneticdisks, such as any of the storage devices in any computer(s) or thelike, such as may be used to implement the databases, etc. shown in thedrawings. Volatile storage media include dynamic memory, such as mainmemory of such a computer platform. Tangible transmission media includecoaxial cables; copper wire and fiber optics, including the wires thatcomprise a bus within a computer system. Carrier-wave transmission mediamay take the form of electric or electromagnetic signals, or acoustic orlight waves such as those generated during radio frequency (RF) andinfrared (IR) data communications. Common forms of computer-readablemedia therefore include for example: a floppy disk, a flexible disk,hard disk, magnetic tape, any other magnetic medium, a CD-ROM, DVD orDVD-ROM, any other optical medium, punch cards paper tape, any otherphysical storage medium with patterns of holes, a RAM, a ROM, a PROM andEPROM, a FLASH-EPROM, any other memory chip or cartridge, a carrier wavetransporting data or instructions, cables or links transporting such acarrier wave, or any other medium from which a computer may readprogramming code and/or data. Many of these forms of computer readablemedia may be involved in carrying one or more sequences of one or moreinstructions to a processor for execution.

EXAMPLES Example 1—Fuel Production from OCM Produced Ethylene

An example liquid fuel production process is shown in FIG. 34 anddescribed in greater detail below. In this example, an OCM product gascontaining ethylene 3402 is preheated to 200° C. to 500° C. dependingupon the desired process. The ethylene may be from 0.05% to 100% pure.For less than 100% pure, the ethylene containing gas may include CO₂,CO, H₂, H₂O, C₂H₆, CH₄, C₃ or higher hydrocarbons (i.e., C₃₊hydrocarbons), or combinations thereof.

The heated ethylene containing gas 3402 is then flowed through one ormore ethylene conversion reactors, e.g., reactors 3404, 3406 and 3408,each containing a solid acid catalyst. The different reactors mayinclude reactors having the same catalyst for performing a parallelreaction to produce a single product. Alternatively, and in accordancewith certain aspects of the invention, the different reactors mayinclude different catalysts and/or be operated under different reactionconditions to produce different reaction products or product ranges. Thecatalysts may include crystalline catalysts, such as zeolites, e.g.,zeolites ZSM-5, Y, Beta, ZSM-22, ZSM-48, SAPO-34, SAPO-5, SAPO-11,Mordenite, Ferrierite, and others. Alternatively or additionally, thecatalysts may include crystalline mesoporous materials, such as SBA-15,SBA-16, MCM-22, MCM-41, and Al-MCM-41 catalysts, among others. Zeolitesand mesoporous materials can be modified with metals, metal oxides, ormetal ions to enhance ethylene reactivity, product slate selectivity,and/or catalyst stability.

The ethylene reacts with the solid catalyst to make higher carbonoligomers/products (C₃-C₃₀). Carbon number ranges can be targeteddepending on catalyst type and process conditions.

The oligomerized ethylene product stream 3412 exits from the ethyleneconversion reactor(s) and may be used to heat the incoming ethylenecontaining gas 3402, e.g., via a heat exchanger 3414. The product streamis otherwise passed through a series of heat exchangers 3416, 3418, and3420 to cool the oligomerized product and to generate steam 3422. Theproduct stream 3412 is then passed through a flash drum 3424 to condenseheavier products into liquids 3426. Light products 3436, such asC₃-C₄'s, can be recycled back to the ethylene conversion reactor instream 3428 through compressor 3438 for reaction if the C₃-C₄'s areolefinic and/or to control the heat of reaction of the ethyleneconversion reactors 3404, 3406 and 3408. Alternatively, they may berouted through downstream processes, e.g., through hydrogenation reactor3430 in stream 3436. If desired, the liquid fraction 3426 is passedthrough a hydrogenation reactor 3430 to hydrogenate olefins toparaffins/isoparaffins using a Co/Mo, Pd, Ni/Mo or other hydrogenationcatalyst. The oligomerized product 3426 (or optionally hydrogenatedfraction 3432) may then be routed to a distillation column 3434 tofractionate different cuts of products 3440, such as gasoline, jet, anddiesel fuel, fuel blendstocks or aromatics.

Example 2—Performance of an ETL Reaction

In another example, the performance of an ETL reaction is assessed. TheETL reaction is performed in an ETL reactor to yield a gasoline product.Ethylene is introduced to a packed bed of extruded H—Mg-ZSM-5 catalystat a WHSV of about 0.7 hr¹ and a temperature of about 350° C. Theethylene partial pressure is about 1 bar. The reactor effluent ischilled to a condenser temperature of about −5° C., and a portion of thenon-condensing vapors are recycled by a gas pump to the reactor inlet.In this example, the volumetric recycle-to-feed ratio is about 2:1. Thefeed to the reactor is comprised of the combination of ethylene feed andrecycled vapors, yielding an ethylene concentration at the reactor inletof about 25%. The product slate and performance of the catalyst preparedaccording to the methods described herein are detailed in FIG. 5.

Example 3—ETL Reaction Products

ETL processes are conducted as described in this disclosure, and thereaction product properties are measured. During the ETL oligomerizationprocess, a small amount of coke is produced. Over time, the coke willdeactivate the catalyst below desired levels. Catalyst activity can berestored to full activity by removing the coke by oxidation. Thecatalyst is robust to coke and decoke cycles. As the catalystdeactivates, the product slate changes. A freshly regenerated catalystbed will be more selective to aromatics and paraffins. Overtime, thecatalyst bed will become less selective toward aromatics and paraffinsand more selective toward olefins. FIG. 35 shows the effect thatcatalyst time on stream for a single reactor has on the product slatecomposition. Time on stream (TOS) progresses along the x-axis from startof run (SOR) to end of run (EOR), and the width of product bands on they-axis shows their relative abundance. From top to bottom, the productsshown are C₁₀₊ compounds, aromatics, naphthenes, isoparaffins,N-paraffins, propane/butane, propene/butene, C₅₊ olefins, and othercompounds.

ETL processes are conducted with different feedstocks, and the reactoroutput is compared with PIONA analysis (paraffin content, isoparaffincontent, olefins content, naphthenes content, and aromatics content), asshown in FIGS. 36A-36E. The feedstocks compared are ethylene (FIG. 36A),propylene (FIG. 36B), butylene (FIG. 36C), 50:50 ethylene/propylene(FIG. 36D), and 50:50 ethylene/butylene (FIG. 36E). The liquid productsfrom the different feeds are comparable in composition and carbon numberdistribution, showing the robustness of the process with respect to feedcomposition.

ETL processes are conducted at different peak catalyst bed temperatures,and the effect on product composition is evaluated, as shown in FIG. 37.The x-axis shows the temperature from 315° C. to 385° C., and the y-axisshows the liquid mol % of various product components. From top tobottom, the product components are C10+ compounds, aromatics,naphthenes, olefin, isoparaffins, and paraffins.

Different segments of ETL product components can be directed for use indifferent fractions. For example, a separations process can be employedto separate a jet fraction (comprising, e.g., C₁₀₊ compounds) from agasoline fraction (comprising, e.g., C⁹⁻ compounds), as shown in FIG.38. In some cases, the ETL product stream can comprise about 65%gasoline fraction components and about 35% jet fraction components.

Reactor operating conditions can impact the reactor performance, and canfavor the production of components for a particular product slate. Forexample, operating conditions and reactor performance for the productioncan be those shown in Table 3, favoring the production of gasolinecomponents. The resulting product can have a stream composition as shownin Table 4, and can be characterized by the properties shown in Table 5(center column), with reference to the specification for RBOB (leftcolumn).

In another example, operating conditions can favor the production ofaromatics, such as the operating conditions and reactor performanceshown in Table 6. The resulting product can have a stream composition asshown in Table 7.

TABLE 3 Operating conditions and reactor performance, gasoline ETLGasoline Inlet T (° C.) 300 Outlet T (° C.) 383 Inlet P (Barg) 25 OutletP (Barg) 25 WHSV (h⁻¹) 1.4 C₂₌ conversion  >99% C₅₊ Selectivity   63%Composition mol % Inlet CH₄ 95 C₂H₄ 5 C balance 99.1%

TABLE 4 Outlet stream composition, gasoline (in C mol %) n-paraffinsi-paraffins olefins napthenes aromatics Total C1 0.00% 0.00% 0.00% 0.00%0.00% 0.00% C2 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% C3 9.62% 0.00% 1.90%0.00% 0.00% 11.52% C4 7.51% 14.92% 2.93% 0.00% 0.00% 25.36% C5 2.87%8.20% 1.70% 2.00% 0.00% 14.77% C6 0.45% 6.88% 1.57% 1.46% 0.00% 10.36%C7 0.16% 3.34% 0.91% 0.90% 3.35% 8.65% C8 0.08% 1.02% 0.26% 1.06% 6.63%9.06% C9 0.03% 0.91% 0.24% 0.48% 6.53% 8.19% C10 0.03% 0.76% 0.02% 0.18%4.14% 5.12% C11+ 6.96%

TABLE 5 Gasoline fuel properties RBOB Product specification propertiesChemical [max.] Benzene (Vol %) 1.30%  0.97% Aromatics (Vol %)   50%35.31% Olefins (Vol %)   25%  24.6% Octane [min] RON — 96.9 MON 82 84.9Tot. Octane 87 90.9 Distillation [max] RVP (psi) 15 9.37 10% (° C.) 7057.67 50% (° C.) 121 113.78 90% (° C.) 190 161.28 FBP (° C.) 221 192.39Oxidation stability Induction time (min) 240 >240

TABLE 6 Operating conditions and reactor performance, aromatics ETLGasoline Inlet T (° C.) 300 Outlet T (° C.) 383 Inlet P (B arg) 25Outlet P (Barg) 25 WHSV (h⁻¹) 1.4 C₂₌ conversion  >99% C₅₊ Selectivity  63% Composition mol % Inlet CH₄ 95 C₂H₄ 5 C balance 99.1%

TABLE 7 Outlet stream composition, aromatics (in C mol %) n-paraffinsi-paraffins olefins napthenes aromatics Total C1 0.00% 0.00% 0.00% 0.00%0.00% 0.00% C2 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% C3 9.62% 0.00% 1.90%0.00% 0.00% 11.52% C4 7.51% 14.92% 2.93% 0.00% 0.00% 25.36% C5 2.87%8.20% 1.70% 2.00% 0.00% 14.77% C6 0.45% 6.88% 1.57% 1.46% 0.00% 10.36%C7 0.16% 3.34% 0.91% 0.90% 3.35% 8.65% C8 0.08% 1.02% 0.26% 1.06% 6.63%9.06% C9 0.03% 0.91% 0.24% 0.48% 6.53% 8.19% C10 0.03% 0.76% 0.02% 0.18%4.14% 5.12% C11+ 6.96%

Example 4—ETL Catalyst Formation and Use

To form ETL catalyst, base material, dopant, and binder are mixed indesired ratios and then extruded. The target catalyst form strength isto maintain particle crush strength above 3 N/mm. The crush strengththreshold is selected based upon the expected stress on individualparticles in a commercial scale reactor. As shown in FIG. 39, the ETLcatalyst baseline formulation is above the crush strength threshold. Ifdesired, stronger catalyst forms can be achieved by tailoring the activecatalyst to binder ratio.

Catalyst aging can be accelerated by changing process conditions, suchas WHSV. Catalyst aging can be accelerated without changing processinputs. FIG. 40 shows catalyst aging measured by fractional ethyleneconversion (y-axis) as a function of time on stream (TOS, x-axis) inhours. Catalyst aging under typical commercial conditions is shown bythe curve on the right, and catalyst aging under accelerated conditionsis shown by the curve on the left.

The catalyst used can be robust to a number of process and regenerationcycles, with little to no impact on the product composition. FIG. 41shows the product composition produced by a reactor in its first cycle,i.e. no catalyst regeneration (left side) compared to a reactor in itstenth cycle, i.e. nine catalyst regenerations (right side). The productcomponents graphed, from top to bottom, are C₁₁₊ compounds, aromatics,naphthenes, olefins, iso-paraffins, and paraffins.

Systems and methods of the present disclosure can be combined with ormodified by other systems and methods, such as those described in U.S.Pat. Nos. 2,943,125, 3,686,350, 4,101,600, 8,624,042, and 5,792,895,U.S. patent application Ser. No. 14/099,614 and PCT/US2013/073657, eachof which is entirely incorporated herein by reference.

It should be understood from the foregoing that, while particularimplementations have been illustrated and described, variousmodifications can be made thereto and are contemplated herein. It isalso not intended that the invention be limited by the specific examplesprovided within the specification. While the invention has beendescribed with reference to the aforementioned specification, thedescriptions and illustrations of the preferable embodiments herein arenot meant to be construed in a limiting sense. Furthermore, it shall beunderstood that all aspects of the invention are not limited to thespecific depictions, configurations or relative proportions set forthherein which depend upon a variety of conditions and variables. Variousmodifications in form and detail of the embodiments of the inventionwill be apparent to a person skilled in the art. It is thereforecontemplated that the invention shall also cover any such modifications,variations and equivalents. It is intended that the following claimsdefine the scope of the invention and that methods and structures withinthe scope of these claims and their equivalents be covered thereby.

1.-20. (canceled)
 21. A method of producing a plurality of hydrocarbonproducts including hydrocarbon compounds with two or more carbon atoms(C₂₊ compounds), comprising: (a) directing methane and an oxidant to anoxidative coupling of methane (OCM) reactor that is upstream of apost-bed cracking (PBC) unit, wherein the OCM reactor is configured tofacilitate an OCM reaction using the methane and the oxidant to generatethe C₂₊ compounds including ethylene and one or more alkanes, andwherein the PBC unit is configured to convert the one or more alkanes,including ethane, to one or more alkenes, including ethylene; (b) in theOCM reactor, reacting the methane and the oxidant in the OCM reaction togenerate an OCM product stream and heat, wherein the OCM product streamcomprises ethylene and one or more alkanes; (c) directing the OCMproduct stream to the PBC unit; (d) in the PBC unit, subjecting the OCMproduct stream to thermal cracking under conditions that crack ethane toethylene, wherein the thermal cracking is conducted at least in partwith the heat from (b), thereby producing a PBC product streamcomprising ethylene; (e) directing the PBC product stream to aseparations module, and, in the separations module, separating ethanefrom the PBC product stream to generate an ethane stream; and (f)directing the ethane stream to the PBC unit.
 22. The method according toclaim 21, wherein the PBC unit is a section of the OCM reactor.
 23. Themethod according to claim 21, wherein the PBC unit is separate from theOCM reactor.
 24. The method according to claim 23, wherein the PBC unitis in thermal communication with the OCM reactor.
 25. The methodaccording to claim 21, wherein an inlet temperature of the OCM reactoris from about 400° C. to about 600° C. and a pressure of the OCM reactoris from about 15 psig to 150 psig.
 26. The method according to claim 25,wherein the OCM reaction has a C₂₊ selectivity of at least 50%.
 27. Themethod according to claim 21, wherein the separations module comprises ade-methanizer, and in the de-methanizer, separating C₁ compoundscontained in the PBC product stream from C₂₊ compounds contained in thePBC product stream, directing the C₁ compounds to a methanator to formmethane, and directing at least a portion of the methane formed in themethanator to the OCM reactor.
 28. The method according to claim 21,wherein directing the ethane stream to the PBC unit results in acracking capacity of the PBC unit being at least 70% saturated.
 29. Themethod according to claim 21, wherein a molar ratio of methane to ethanein the PBC unit is from 1:1 to 15:1.
 30. The method according to claim21, wherein the OCM reactor comprises a nanowire OCM catalyst material.31. The method according to claim 21, further comprising: directing astream comprising at least one of C₃ compounds or C₄ compounds to adownstream region of the PBC unit.
 32. The method according to claim 21,wherein the amount of ethane converted to ethylene is at least about 50%of a maximum amount of ethane that can be converted to ethylene in thePBC unit.
 33. The method according to claim 21, further comprising: (i)directing a natural gas stream having a methane to ethane ratio of 1:1to 40:1 to a process gas compressor downstream of the PBC unit; and (ii)directing the PBC product stream to the process gas compressor prior to(e).
 34. A system for producing a plurality of hydrocarbon productsincluding hydrocarbon compounds with two or more carbon atoms (C₂₊compounds), comprising: (a) an oxidative coupling of methane (OCM)reactor comprising an OCM catalyst and fluidly connected at one or morereactor inlets to a source of methane and a source of oxidant, whereinthe OCM reactor is configured to generate an OCM product stream and heatfrom the source of methane and the source of oxidant, wherein the OCMproduct stream comprises C₂₊ compounds including ethylene and one ormore alkanes, including ethane; (b) a post-bed cracking (PBC) unitfluidly connected to the OCM reactor and downstream of the OCM catalyst,wherein the PBC unit is configured to thermally crack the one or morealkanes, including ethane, contained in the OCM product stream to one ormore alkenes, including ethylene, using heat generated in the OCMreactor, to thereby produce a PBC product stream comprising ethylene andethane; and (c) a separations module downstream of and fluidly connectedto the PBC unit, wherein the separations module comprises a de-ethanizerconfigured to produce an ethane stream from the ethane contained in thePBC product stream and to feed the ethane stream to the PBC unit. 35.The system according to claim 34, wherein the separations modulecomprises a de-methanizer configured to separate C₁ compounds containedin the PBC product stream from C₂₊ compounds contained in the PBCproduct stream.
 36. The system according to claim 35, wherein theseparations module comprises a methanator fluidly connected to thede-methanizer and to the OCM reactor, wherein the methanator isconfigured to receive C₁ compounds from the de-methanizer, to produce amethane stream from the C₁ compounds, and to feed at least a portion ofthe methane stream to the OCM reactor.
 37. The system according to claim34, wherein the PBC unit is a section of the OCM reactor.
 38. The systemaccording to claim 34, wherein the PBC unit is separate from the OCMreactor.